code-python.md

---
title: "Agent SDK reference - Python"
source: "https://code.claude.com/docs/en/agent-sdk/python"
category: "code"
generated: true
---
> ## Documentation Index
> Fetch the complete documentation index at: https://code.claude.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Agent SDK reference - Python

> Complete API reference for the Python Agent SDK, including all functions, types, and classes.

## Installation

```bash theme={null}
pip install claude-agent-sdk
```

## Choosing between `query()` and `ClaudeSDKClient`

The Python SDK provides two ways to interact with Claude Code:

### Quick comparison

| Feature             | `query()`                                      | `ClaudeSDKClient`                  |
| :------------------ | :--------------------------------------------- | :--------------------------------- |
| **Session**         | Creates a new session by default               | Reuses same session                |
| **Conversation**    | Single exchange                                | Multiple exchanges in same context |
| **Connection**      | Managed automatically                          | Manual control                     |
| **Streaming Input** | ✅ Supported                                    | ✅ Supported                        |
| **Interrupts**      | ❌ Not supported                                | ✅ Supported                        |
| **Hooks**           | ✅ Supported                                    | ✅ Supported                        |
| **Custom Tools**    | ✅ Supported                                    | ✅ Supported                        |
| **Continue Chat**   | Manual via `continue_conversation` or `resume` | ✅ Automatic                        |
| **Use Case**        | One-off tasks                                  | Continuous conversations           |

### When to use `query()` (one-off tasks)

**Best for:**

* One-off questions where you don't need conversation history
* Independent tasks that don't require context from previous exchanges
* Simple automation scripts
* When you want a fresh start each time

### When to use `ClaudeSDKClient` (continuous conversation)

**Best for:**

* **Continuing conversations** - When you need Claude to remember context
* **Follow-up questions** - Building on previous responses
* **Interactive applications** - Chat interfaces, REPLs
* **Response-driven logic** - When next action depends on Claude's response
* **Session control** - Managing conversation lifecycle explicitly

## Functions

### `query()`

Creates a new session for each interaction with Claude Code by default. Returns an async iterator that yields messages as they arrive. Each call to `query()` starts fresh with no memory of previous interactions unless you pass `continue_conversation=True` or `resume` in [`ClaudeAgentOptions`](#claudeagentoptions). See [Sessions](./code-agent-sdk/sessions.md).

```python theme={null}
async def query(
    *,
    prompt: str | AsyncIterable[dict[str, Any]],
    options: ClaudeAgentOptions | None = None,
    transport: Transport | None = None
) -> AsyncIterator[Message]
```

#### Parameters

| Parameter   | Type                         | Description                                                                |
| :---------- | :--------------------------- | :------------------------------------------------------------------------- |
| `prompt`    | `str \| AsyncIterable[dict]` | The input prompt as a string or async iterable for streaming mode          |
| `options`   | `ClaudeAgentOptions \| None` | Optional configuration object (defaults to `ClaudeAgentOptions()` if None) |
| `transport` | `Transport \| None`          | Optional custom transport for communicating with the CLI process           |

#### Returns

Returns an `AsyncIterator[Message]` that yields messages from the conversation.

#### Example - With options

```python theme={null}
import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions


async def main():
    options = ClaudeAgentOptions(
        system_prompt="You are an expert Python developer",
        permission_mode="acceptEdits",
        cwd="/home/user/project",
    )

    async for message in query(prompt="Create a Python web server", options=options):
        print(message)


asyncio.run(main())
```

### `tool()`

Decorator for defining MCP tools with type safety.

```python theme={null}
def tool(
    name: str,
    description: str,
    input_schema: type | dict[str, Any],
    annotations: ToolAnnotations | None = None
) -> Callable[[Callable[[Any], Awaitable[dict[str, Any]]]], SdkMcpTool[Any]]
```

#### Parameters

| Parameter      | Type                                            | Description                                                         |
| :------------- | :---------------------------------------------- | :------------------------------------------------------------------ |
| `name`         | `str`                                           | Unique identifier for the tool                                      |
| `description`  | `str`                                           | Human-readable description of what the tool does                    |
| `input_schema` | `type \| dict[str, Any]`                        | Schema defining the tool's input parameters (see below)             |
| `annotations`  | [`ToolAnnotations`](#toolannotations)` \| None` | Optional MCP tool annotations providing behavioral hints to clients |

#### Input schema options

1. **Simple type mapping** (recommended):

   ```python theme={null}
   {"text": str, "count": int, "enabled": bool}
   ```

2. **JSON Schema format** (for complex validation):
   ```python theme={null}
   {
       "type": "object",
       "properties": {
           "text": {"type": "string"},
           "count": {"type": "integer", "minimum": 0},
       },
       "required": ["text"],
   }
   ```

#### Returns

A decorator function that wraps the tool implementation and returns an `SdkMcpTool` instance.

#### Example

```python theme={null}
from claude_agent_sdk import tool
from typing import Any


@tool("greet", "Greet a user", {"name": str})
async def greet(args: dict[str, Any]) -> dict[str, Any]:
    return {"content": [{"type": "text", "text": f"Hello, {args['name']}!"}]}
```

#### `ToolAnnotations`

Re-exported from `mcp.types` (also available as `from claude_agent_sdk import ToolAnnotations`). All fields are optional hints; clients should not rely on them for security decisions.

| Field             | Type           | Default | Description                                                                                                                                          |
| :---------------- | :------------- | :------ | :--------------------------------------------------------------------------------------------------------------------------------------------------- |
| `title`           | `str \| None`  | `None`  | Human-readable title for the tool                                                                                                                    |
| `readOnlyHint`    | `bool \| None` | `False` | If `True`, the tool does not modify its environment                                                                                                  |
| `destructiveHint` | `bool \| None` | `True`  | If `True`, the tool may perform destructive updates (only meaningful when `readOnlyHint` is `False`)                                                 |
| `idempotentHint`  | `bool \| None` | `False` | If `True`, repeated calls with the same arguments have no additional effect (only meaningful when `readOnlyHint` is `False`)                         |
| `openWorldHint`   | `bool \| None` | `True`  | If `True`, the tool interacts with external entities (for example, web search). If `False`, the tool's domain is closed (for example, a memory tool) |

```python theme={null}
from claude_agent_sdk import tool, ToolAnnotations
from typing import Any


@tool(
    "search",
    "Search the web",
    {"query": str},
    annotations=ToolAnnotations(readOnlyHint=True, openWorldHint=True),
)
async def search(args: dict[str, Any]) -> dict[str, Any]:
    return {"content": [{"type": "text", "text": f"Results for: {args['query']}"}]}
```

### `create_sdk_mcp_server()`

Create an in-process MCP server that runs within your Python application.

```python theme={null}
def create_sdk_mcp_server(
    name: str,
    version: str = "1.0.0",
    tools: list[SdkMcpTool[Any]] | None = None
) -> McpSdkServerConfig
```

#### Parameters

| Parameter | Type                            | Default   | Description                                           |
| :-------- | :------------------------------ | :-------- | :---------------------------------------------------- |
| `name`    | `str`                           | -         | Unique identifier for the server                      |
| `version` | `str`                           | `"1.0.0"` | Server version string                                 |
| `tools`   | `list[SdkMcpTool[Any]] \| None` | `None`    | List of tool functions created with `@tool` decorator |

#### Returns

Returns an `McpSdkServerConfig` object that can be passed to `ClaudeAgentOptions.mcp_servers`.

#### Example

```python theme={null}
from claude_agent_sdk import tool, create_sdk_mcp_server


@tool("add", "Add two numbers", {"a": float, "b": float})
async def add(args):
    return {"content": [{"type": "text", "text": f"Sum: {args['a'] + args['b']}"}]}


@tool("multiply", "Multiply two numbers", {"a": float, "b": float})
async def multiply(args):
    return {"content": [{"type": "text", "text": f"Product: {args['a'] * args['b']}"}]}


calculator = create_sdk_mcp_server(
    name="calculator",
    version="2.0.0",
    tools=[add, multiply],  # Pass decorated functions
)

# Use with Claude
options = ClaudeAgentOptions(
    mcp_servers={"calc": calculator},
    allowed_tools=["mcp__calc__add", "mcp__calc__multiply"],
)
```

### `list_sessions()`

Lists past sessions with metadata. Filter by project directory or list sessions across all projects. Synchronous; returns immediately.

```python theme={null}
def list_sessions(
    directory: str | None = None,
    limit: int | None = None,
    include_worktrees: bool = True
) -> list[SDKSessionInfo]
```

#### Parameters

| Parameter           | Type          | Default | Description                                                                           |
| :------------------ | :------------ | :------ | :------------------------------------------------------------------------------------ |
| `directory`         | `str \| None` | `None`  | Directory to list sessions for. When omitted, returns sessions across all projects    |
| `limit`             | `int \| None` | `None`  | Maximum number of sessions to return                                                  |
| `include_worktrees` | `bool`        | `True`  | When `directory` is inside a git repository, include sessions from all worktree paths |

#### Return type: `SDKSessionInfo`

| Property        | Type          | Description                                                          |
| :-------------- | :------------ | :------------------------------------------------------------------- |
| `session_id`    | `str`         | Unique session identifier                                            |
| `summary`       | `str`         | Display title: custom title, auto-generated summary, or first prompt |
| `last_modified` | `int`         | Last modified time in milliseconds since epoch                       |
| `file_size`     | `int \| None` | Session file size in bytes (`None` for remote storage backends)      |
| `custom_title`  | `str \| None` | User-set session title                                               |
| `first_prompt`  | `str \| None` | First meaningful user prompt in the session                          |
| `git_branch`    | `str \| None` | Git branch at the end of the session                                 |
| `cwd`           | `str \| None` | Working directory for the session                                    |
| `tag`           | `str \| None` | User-set session tag (see [`tag_session()`](#tag_session))           |
| `created_at`    | `int \| None` | Session creation time in milliseconds since epoch                    |

#### Example

Print the 10 most recent sessions for a project. Results are sorted by `last_modified` descending, so the first item is the newest. Omit `directory` to search across all projects.

```python theme={null}
from claude_agent_sdk import list_sessions

for session in list_sessions(directory="/path/to/project", limit=10):
    print(f"{session.summary} ({session.session_id})")
```

### `get_session_messages()`

Retrieves messages from a past session. Synchronous; returns immediately.

```python theme={null}
def get_session_messages(
    session_id: str,
    directory: str | None = None,
    limit: int | None = None,
    offset: int = 0
) -> list[SessionMessage]
```

#### Parameters

| Parameter    | Type          | Default  | Description                                                       |
| :----------- | :------------ | :------- | :---------------------------------------------------------------- |
| `session_id` | `str`         | required | The session ID to retrieve messages for                           |
| `directory`  | `str \| None` | `None`   | Project directory to look in. When omitted, searches all projects |
| `limit`      | `int \| None` | `None`   | Maximum number of messages to return                              |
| `offset`     | `int`         | `0`      | Number of messages to skip from the start                         |

#### Return type: `SessionMessage`

| Property             | Type                           | Description               |
| :------------------- | :----------------------------- | :------------------------ |
| `type`               | `Literal["user", "assistant"]` | Message role              |
| `uuid`               | `str`                          | Unique message identifier |
| `session_id`         | `str`                          | Session identifier        |
| `message`            | `Any`                          | Raw message content       |
| `parent_tool_use_id` | `None`                         | Reserved for future use   |

#### Example

```python theme={null}
from claude_agent_sdk import list_sessions, get_session_messages

sessions = list_sessions(limit=1)
if sessions:
    messages = get_session_messages(sessions[0].session_id)
    for msg in messages:
        print(f"[{msg.type}] {msg.uuid}")
```

### `get_session_info()`

Reads metadata for a single session by ID without scanning the full project directory. Synchronous; returns immediately.

```python theme={null}
def get_session_info(
    session_id: str,
    directory: str | None = None,
) -> SDKSessionInfo | None
```

#### Parameters

| Parameter    | Type          | Default  | Description                                                            |
| :----------- | :------------ | :------- | :--------------------------------------------------------------------- |
| `session_id` | `str`         | required | UUID of the session to look up                                         |
| `directory`  | `str \| None` | `None`   | Project directory path. When omitted, searches all project directories |

Returns [`SDKSessionInfo`](#return-type-sdksessioninfo), or `None` if the session is not found.

#### Example

Look up a single session's metadata without scanning the project directory. Useful when you already have a session ID from a previous run.

```python theme={null}
from claude_agent_sdk import get_session_info

info = get_session_info("550e8400-e29b-41d4-a716-446655440000")
if info:
    print(f"{info.summary} (branch: {info.git_branch}, tag: {info.tag})")
```

### `rename_session()`

Renames a session by appending a custom-title entry. Repeated calls are safe; the most recent title wins. Synchronous.

```python theme={null}
def rename_session(
    session_id: str,
    title: str,
    directory: str | None = None,
) -> None
```

#### Parameters

| Parameter    | Type          | Default  | Description                                                            |
| :----------- | :------------ | :------- | :--------------------------------------------------------------------- |
| `session_id` | `str`         | required | UUID of the session to rename                                          |
| `title`      | `str`         | required | New title. Must be non-empty after stripping whitespace                |
| `directory`  | `str \| None` | `None`   | Project directory path. When omitted, searches all project directories |

Raises `ValueError` if `session_id` is not a valid UUID or `title` is empty; `FileNotFoundError` if the session cannot be found.

#### Example

Rename the most recent session so it's easier to find later. The new title appears in [`SDKSessionInfo.custom_title`](#return-type-sdksessioninfo) on subsequent reads.

```python theme={null}
from claude_agent_sdk import list_sessions, rename_session

sessions = list_sessions(directory="/path/to/project", limit=1)
if sessions:
    rename_session(sessions[0].session_id, "Refactor auth module")
```

### `tag_session()`

Tags a session. Pass `None` to clear the tag. Repeated calls are safe; the most recent tag wins. Synchronous.

```python theme={null}
def tag_session(
    session_id: str,
    tag: str | None,
    directory: str | None = None,
) -> None
```

#### Parameters

| Parameter    | Type          | Default  | Description                                                            |
| :----------- | :------------ | :------- | :--------------------------------------------------------------------- |
| `session_id` | `str`         | required | UUID of the session to tag                                             |
| `tag`        | `str \| None` | required | Tag string, or `None` to clear. Unicode-sanitized before storing       |
| `directory`  | `str \| None` | `None`   | Project directory path. When omitted, searches all project directories |

Raises `ValueError` if `session_id` is not a valid UUID or `tag` is empty after sanitization; `FileNotFoundError` if the session cannot be found.

#### Example

Tag a session, then filter by that tag on a later read. Pass `None` to clear an existing tag.

```python theme={null}
from claude_agent_sdk import list_sessions, tag_session

# Tag a session
tag_session("550e8400-e29b-41d4-a716-446655440000", "needs-review")

# Later: find all sessions with that tag
for session in list_sessions(directory="/path/to/project"):
    if session.tag == "needs-review":
        print(session.summary)
```

## Classes

### `ClaudeSDKClient`

**Maintains a conversation session across multiple exchanges.** This is the Python equivalent of how the TypeScript SDK's `query()` function works internally - it creates a client object that can continue conversations.

#### Key Features

* **Session continuity**: Maintains conversation context across multiple `query()` calls
* **Same conversation**: The session retains previous messages
* **Interrupt support**: Can stop execution mid-task
* **Explicit lifecycle**: You control when the session starts and ends
* **Response-driven flow**: Can react to responses and send follow-ups
* **Custom tools and hooks**: Supports custom tools (created with `@tool` decorator) and hooks

```python theme={null}
class ClaudeSDKClient:
    def __init__(self, options: ClaudeAgentOptions | None = None, transport: Transport | None = None)
    async def connect(self, prompt: str | AsyncIterable[dict] | None = None) -> None
    async def query(self, prompt: str | AsyncIterable[dict], session_id: str = "default") -> None
    async def receive_messages(self) -> AsyncIterator[Message]
    async def receive_response(self) -> AsyncIterator[Message]
    async def interrupt(self) -> None
    async def set_permission_mode(self, mode: str) -> None
    async def set_model(self, model: str | None = None) -> None
    async def rewind_files(self, user_message_id: str) -> None
    async def get_mcp_status(self) -> McpStatusResponse
    async def reconnect_mcp_server(self, server_name: str) -> None
    async def toggle_mcp_server(self, server_name: str, enabled: bool) -> None
    async def stop_task(self, task_id: str) -> None
    async def get_server_info(self) -> dict[str, Any] | None
    async def disconnect(self) -> None
```

#### Methods

| Method                                    | Description                                                                                                                                                       |
| :---------------------------------------- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `__init__(options)`                       | Initialize the client with optional configuration                                                                                                                 |
| `connect(prompt)`                         | Connect to Claude with an optional initial prompt or message stream                                                                                               |
| `query(prompt, session_id)`               | Send a new request in streaming mode                                                                                                                              |
| `receive_messages()`                      | Receive all messages from Claude as an async iterator                                                                                                             |
| `receive_response()`                      | Receive messages until and including a ResultMessage                                                                                                              |
| `interrupt()`                             | Send interrupt signal (only works in streaming mode)                                                                                                              |
| `set_permission_mode(mode)`               | Change the permission mode for the current session                                                                                                                |
| `set_model(model)`                        | Change the model for the current session. Pass `None` to reset to default                                                                                         |
| `rewind_files(user_message_id)`           | Restore files to their state at the specified user message. Requires `enable_file_checkpointing=True`. See [File checkpointing](./code-agent-sdk/file-checkpointing.md) |
| `get_mcp_status()`                        | Get the status of all configured MCP servers. Returns [`McpStatusResponse`](#mcpstatusresponse)                                                                   |
| `reconnect_mcp_server(server_name)`       | Retry connecting to an MCP server that failed or was disconnected                                                                                                 |
| `toggle_mcp_server(server_name, enabled)` | Enable or disable an MCP server mid-session. Disabling removes its tools                                                                                          |
| `stop_task(task_id)`                      | Stop a running background task. A [`TaskNotificationMessage`](#tasknotificationmessage) with status `"stopped"` follows in the message stream                     |
| `get_server_info()`                       | Get server information including session ID and capabilities                                                                                                      |
| `disconnect()`                            | Disconnect from Claude                                                                                                                                            |

#### Context Manager Support

The client can be used as an async context manager for automatic connection management:

```python theme={null}
async with ClaudeSDKClient() as client:
    await client.query("Hello Claude")
    async for message in client.receive_response():
        print(message)
```

> **Important:** When iterating over messages, avoid using `break` to exit early as this can cause asyncio cleanup issues. Instead, let the iteration complete naturally or use flags to track when you've found what you need.

#### Example - Continuing a conversation

```python theme={null}
import asyncio
from claude_agent_sdk import ClaudeSDKClient, AssistantMessage, TextBlock, ResultMessage


async def main():
    async with ClaudeSDKClient() as client:
        # First question
        await client.query("What's the capital of France?")

        # Process response
        async for message in client.receive_response():
            if isinstance(message, AssistantMessage):
                for block in message.content:
                    if isinstance(block, TextBlock):
                        print(f"Claude: {block.text}")

        # Follow-up question - the session retains the previous context
        await client.query("What's the population of that city?")

        async for message in client.receive_response():
            if isinstance(message, AssistantMessage):
                for block in message.content:
                    if isinstance(block, TextBlock):
                        print(f"Claude: {block.text}")

        # Another follow-up - still in the same conversation
        await client.query("What are some famous landmarks there?")

        async for message in client.receive_response():
            if isinstance(message, AssistantMessage):
                for block in message.content:
                    if isinstance(block, TextBlock):
                        print(f"Claude: {block.text}")


asyncio.run(main())
```

#### Example - Streaming input with ClaudeSDKClient

```python theme={null}
import asyncio
from claude_agent_sdk import ClaudeSDKClient


async def message_stream():
    """Generate messages dynamically."""
    yield {
        "type": "user",
        "message": {"role": "user", "content": "Analyze the following data:"},
    }
    await asyncio.sleep(0.5)
    yield {
        "type": "user",
        "message": {"role": "user", "content": "Temperature: 25°C, Humidity: 60%"},
    }
    await asyncio.sleep(0.5)
    yield {
        "type": "user",
        "message": {"role": "user", "content": "What patterns do you see?"},
    }


async def main():
    async with ClaudeSDKClient() as client:
        # Stream input to Claude
        await client.query(message_stream())

        # Process response
        async for message in client.receive_response():
            print(message)

        # Follow-up in same session
        await client.query("Should we be concerned about these readings?")

        async for message in client.receive_response():
            print(message)


asyncio.run(main())
```

#### Example - Using interrupts

```python theme={null}
import asyncio
from claude_agent_sdk import ClaudeSDKClient, ClaudeAgentOptions, ResultMessage


async def interruptible_task():
    options = ClaudeAgentOptions(allowed_tools=["Bash"], permission_mode="acceptEdits")

    async with ClaudeSDKClient(options=options) as client:
        # Start a long-running task
        await client.query("Count from 1 to 100 slowly, using the bash sleep command")

        # Let it run for a bit
        await asyncio.sleep(2)

        # Interrupt the task
        await client.interrupt()
        print("Task interrupted!")

        # Drain the interrupted task's messages (including its ResultMessage)
        async for message in client.receive_response():
            if isinstance(message, ResultMessage):
                print(f"Interrupted task finished with subtype={message.subtype!r}")
                # subtype is "error_during_execution" for interrupted tasks

        # Send a new command
        await client.query("Just say hello instead")

        # Now receive the new response
        async for message in client.receive_response():
            if isinstance(message, ResultMessage) and message.subtype == "success":
                print(f"New result: {message.result}")


asyncio.run(interruptible_task())
```

<Note>
  **Buffer behavior after interrupt:** `interrupt()` sends a stop signal but does not clear the message buffer. Messages already produced by the interrupted task, including its `ResultMessage` (with `subtype="error_during_execution"`), remain in the stream. You must drain them with `receive_response()` before reading the response to a new query. If you send a new query immediately after `interrupt()` and call `receive_response()` only once, you'll receive the interrupted task's messages, not the new query's response.
</Note>

#### Example - Advanced permission control

```python theme={null}
from claude_agent_sdk import ClaudeSDKClient, ClaudeAgentOptions
from claude_agent_sdk.types import (
    PermissionResultAllow,
    PermissionResultDeny,
    ToolPermissionContext,
)


async def custom_permission_handler(
    tool_name: str, input_data: dict, context: ToolPermissionContext
) -> PermissionResultAllow | PermissionResultDeny:
    """Custom logic for tool permissions."""

    # Block writes to system directories
    if tool_name == "Write" and input_data.get("file_path", "").startswith("/system/"):
        return PermissionResultDeny(
            message="System directory write not allowed", interrupt=True
        )

    # Redirect sensitive file operations
    if tool_name in ["Write", "Edit"] and "config" in input_data.get("file_path", ""):
        safe_path = f"./sandbox/{input_data['file_path']}"
        return PermissionResultAllow(
            updated_input={**input_data, "file_path": safe_path}
        )

    # Allow everything else
    return PermissionResultAllow(updated_input=input_data)


async def main():
    options = ClaudeAgentOptions(
        can_use_tool=custom_permission_handler, allowed_tools=["Read", "Write", "Edit"]
    )

    async with ClaudeSDKClient(options=options) as client:
        await client.query("Update the system config file")

        async for message in client.receive_response():
            # Will use sandbox path instead
            print(message)


asyncio.run(main())
```

## Types

<Note>
  **`@dataclass` vs `TypedDict`:** This SDK uses two kinds of types. Classes decorated with `@dataclass` (such as `ResultMessage`, `AgentDefinition`, `TextBlock`) are object instances at runtime and support attribute access: `msg.result`. Classes defined with `TypedDict` (such as `ThinkingConfigEnabled`, `McpStdioServerConfig`, `SyncHookJSONOutput`) are **plain dicts at runtime** and require key access: `config["budget_tokens"]`, not `config.budget_tokens`. The `ClassName(field=value)` call syntax works for both, but only dataclasses produce objects with attributes.
</Note>

### `SdkMcpTool`

Definition for an SDK MCP tool created with the `@tool` decorator.

```python theme={null}
@dataclass
class SdkMcpTool(Generic[T]):
    name: str
    description: str
    input_schema: type[T] | dict[str, Any]
    handler: Callable[[T], Awaitable[dict[str, Any]]]
    annotations: ToolAnnotations | None = None
```

| Property       | Type                                       | Description                                                                                                |
| :------------- | :----------------------------------------- | :--------------------------------------------------------------------------------------------------------- |
| `name`         | `str`                                      | Unique identifier for the tool                                                                             |
| `description`  | `str`                                      | Human-readable description                                                                                 |
| `input_schema` | `type[T] \| dict[str, Any]`                | Schema for input validation                                                                                |
| `handler`      | `Callable[[T], Awaitable[dict[str, Any]]]` | Async function that handles tool execution                                                                 |
| `annotations`  | `ToolAnnotations \| None`                  | Optional MCP tool annotations (e.g., `readOnlyHint`, `destructiveHint`, `openWorldHint`). From `mcp.types` |

### `Transport`

Abstract base class for custom transport implementations. Use this to communicate with the Claude process over a custom channel (for example, a remote connection instead of a local subprocess).

<Warning>
  This is a low-level internal API. The interface may change in future releases. Custom implementations must be updated to match any interface changes.
</Warning>

```python theme={null}
from abc import ABC, abstractmethod
from collections.abc import AsyncIterator
from typing import Any


class Transport(ABC):
    @abstractmethod
    async def connect(self) -> None: ...

    @abstractmethod
    async def write(self, data: str) -> None: ...

    @abstractmethod
    def read_messages(self) -> AsyncIterator[dict[str, Any]]: ...

    @abstractmethod
    async def close(self) -> None: ...

    @abstractmethod
    def is_ready(self) -> bool: ...

    @abstractmethod
    async def end_input(self) -> None: ...
```

| Method            | Description                                                                 |
| :---------------- | :-------------------------------------------------------------------------- |
| `connect()`       | Connect the transport and prepare for communication                         |
| `write(data)`     | Write raw data (JSON + newline) to the transport                            |
| `read_messages()` | Async iterator that yields parsed JSON messages                             |
| `close()`         | Close the connection and clean up resources                                 |
| `is_ready()`      | Returns `True` if the transport can send and receive                        |
| `end_input()`     | Close the input stream (for example, close stdin for subprocess transports) |

Import: `from claude_agent_sdk import Transport`

### `ClaudeAgentOptions`

Configuration dataclass for Claude Code queries.

```python theme={null}
@dataclass
class ClaudeAgentOptions:
    tools: list[str] | ToolsPreset | None = None
    allowed_tools: list[str] = field(default_factory=list)
    system_prompt: str | SystemPromptPreset | None = None
    mcp_servers: dict[str, McpServerConfig] | str | Path = field(default_factory=dict)
    strict_mcp_config: bool = False
    permission_mode: PermissionMode | None = None
    continue_conversation: bool = False
    resume: str | None = None
    max_turns: int | None = None
    max_budget_usd: float | None = None
    disallowed_tools: list[str] = field(default_factory=list)
    model: str | None = None
    fallback_model: str | None = None
    betas: list[SdkBeta] = field(default_factory=list)
    output_format: dict[str, Any] | None = None
    permission_prompt_tool_name: str | None = None
    cwd: str | Path | None = None
    cli_path: str | Path | None = None
    settings: str | None = None
    add_dirs: list[str | Path] = field(default_factory=list)
    env: dict[str, str] = field(default_factory=dict)
    extra_args: dict[str, str | None] = field(default_factory=dict)
    max_buffer_size: int | None = None
    debug_stderr: Any = sys.stderr  # Deprecated
    stderr: Callable[[str], None] | None = None
    can_use_tool: CanUseTool | None = None
    hooks: dict[HookEvent, list[HookMatcher]] | None = None
    user: str | None = None
    include_partial_messages: bool = False
    include_hook_events: bool = False
    fork_session: bool = False
    agents: dict[str, AgentDefinition] | None = None
    setting_sources: list[SettingSource] | None = None
    sandbox: SandboxSettings | None = None
    plugins: list[SdkPluginConfig] = field(default_factory=list)
    max_thinking_tokens: int | None = None  # Deprecated: use thinking instead
    thinking: ThinkingConfig | None = None
    effort: EffortLevel | None = None
    enable_file_checkpointing: bool = False
    session_store: SessionStore | None = None
    session_store_flush: SessionStoreFlushMode = "batched"
```

| Property                      | Type                                                                                  | Default                            | Description                                                                                                                                                                                                                                                                                             |
| :---------------------------- | :------------------------------------------------------------------------------------ | :--------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `tools`                       | `list[str] \| ToolsPreset \| None`                                                    | `None`                             | Tools configuration. Use `{"type": "preset", "preset": "claude_code"}` for Claude Code's default tools                                                                                                                                                                                                  |
| `allowed_tools`               | `list[str]`                                                                           | `[]`                               | Tools to auto-approve without prompting. This does not restrict Claude to only these tools; unlisted tools fall through to `permission_mode` and `can_use_tool`. Use `disallowed_tools` to block tools. See [Permissions](./code-agent-sdk/permissions.md#allow-and-deny-rules)                               |
| `system_prompt`               | `str \| SystemPromptPreset \| None`                                                   | `None`                             | System prompt configuration. Pass a string for custom prompt, or use `{"type": "preset", "preset": "claude_code"}` for Claude Code's system prompt. Add `"append"` to extend the preset                                                                                                                 |
| `mcp_servers`                 | `dict[str, McpServerConfig] \| str \| Path`                                           | `{}`                               | MCP server configurations or path to config file                                                                                                                                                                                                                                                        |
| `strict_mcp_config`           | `bool`                                                                                | `False`                            | When `True`, use only the servers passed in `mcp_servers` and ignore project `.mcp.json`, user settings, and plugin-provided MCP servers. Maps to the CLI `--strict-mcp-config` flag                                                                                                                    |
| `permission_mode`             | `PermissionMode \| None`                                                              | `None`                             | Permission mode for tool usage                                                                                                                                                                                                                                                                          |
| `continue_conversation`       | `bool`                                                                                | `False`                            | Continue the most recent conversation                                                                                                                                                                                                                                                                   |
| `resume`                      | `str \| None`                                                                         | `None`                             | Session ID to resume                                                                                                                                                                                                                                                                                    |
| `max_turns`                   | `int \| None`                                                                         | `None`                             | Maximum agentic turns (tool-use round trips)                                                                                                                                                                                                                                                            |
| `max_budget_usd`              | `float \| None`                                                                       | `None`                             | Stop the query when the client-side cost estimate reaches this USD value. Compared against the same estimate as `total_cost_usd`; see [Track cost and usage](./code-agent-sdk/cost-tracking.md) for accuracy caveats                                                                                          |
| `disallowed_tools`            | `list[str]`                                                                           | `[]`                               | Tools to deny. A bare name such as `"Bash"` removes the tool from Claude's context. A scoped rule such as `"Bash(rm *)"` leaves the tool available and denies matching calls in every permission mode, including `bypassPermissions`. See [Permissions](./code-agent-sdk/permissions.md#allow-and-deny-rules) |
| `enable_file_checkpointing`   | `bool`                                                                                | `False`                            | Enable file change tracking for rewinding. See [File checkpointing](./code-agent-sdk/file-checkpointing.md)                                                                                                                                                                                                   |
| `model`                       | `str \| None`                                                                         | `None`                             | Claude model to use                                                                                                                                                                                                                                                                                     |
| `fallback_model`              | `str \| None`                                                                         | `None`                             | Fallback model to use if the primary model fails                                                                                                                                                                                                                                                        |
| `betas`                       | `list[SdkBeta]`                                                                       | `[]`                               | Beta features to enable. See [`SdkBeta`](#sdkbeta) for available options                                                                                                                                                                                                                                |
| `output_format`               | `dict[str, Any] \| None`                                                              | `None`                             | Output format for structured responses (e.g., `{"type": "json_schema", "schema": {...}}`). See [Structured outputs](./code-agent-sdk/structured-outputs.md) for details                                                                                                                                       |
| `permission_prompt_tool_name` | `str \| None`                                                                         | `None`                             | MCP tool name for permission prompts                                                                                                                                                                                                                                                                    |
| `cwd`                         | `str \| Path \| None`                                                                 | `None`                             | Current working directory                                                                                                                                                                                                                                                                               |
| `cli_path`                    | `str \| Path \| None`                                                                 | `None`                             | Custom path to the Claude Code CLI executable                                                                                                                                                                                                                                                           |
| `settings`                    | `str \| None`                                                                         | `None`                             | Path to settings file                                                                                                                                                                                                                                                                                   |
| `add_dirs`                    | `list[str \| Path]`                                                                   | `[]`                               | Additional directories Claude can access                                                                                                                                                                                                                                                                |
| `env`                         | `dict[str, str]`                                                                      | `{}`                               | Environment variables merged on top of the inherited process environment. See [Environment variables](./code-env-vars.md) for variables the underlying CLI reads, and [Handle slow or stalled API responses](#handle-slow-or-stalled-api-responses) for timeout-related variables                             |
| `extra_args`                  | `dict[str, str \| None]`                                                              | `{}`                               | Additional CLI arguments to pass directly to the CLI                                                                                                                                                                                                                                                    |
| `max_buffer_size`             | `int \| None`                                                                         | `None`                             | Maximum bytes when buffering CLI stdout                                                                                                                                                                                                                                                                 |
| `debug_stderr`                | `Any`                                                                                 | `sys.stderr`                       | *Deprecated* - File-like object for debug output. Use `stderr` callback instead                                                                                                                                                                                                                         |
| `stderr`                      | `Callable[[str], None] \| None`                                                       | `None`                             | Callback function for stderr output from CLI                                                                                                                                                                                                                                                            |
| `can_use_tool`                | [`CanUseTool`](#canusetool) ` \| None`                                                | `None`                             | Tool permission callback function. See [Permission types](#canusetool) for details                                                                                                                                                                                                                      |
| `hooks`                       | `dict[HookEvent, list[HookMatcher]] \| None`                                          | `None`                             | Hook configurations for intercepting events                                                                                                                                                                                                                                                             |
| `user`                        | `str \| None`                                                                         | `None`                             | User identifier                                                                                                                                                                                                                                                                                         |
| `include_partial_messages`    | `bool`                                                                                | `False`                            | Include partial message streaming events. When enabled, [`StreamEvent`](#streamevent) messages are yielded                                                                                                                                                                                              |
| `include_hook_events`         | `bool`                                                                                | `False`                            | Include hook lifecycle events in the message stream as `HookEventMessage` objects                                                                                                                                                                                                                       |
| `fork_session`                | `bool`                                                                                | `False`                            | When resuming with `resume`, fork to a new session ID instead of continuing the original session                                                                                                                                                                                                        |
| `agents`                      | `dict[str, AgentDefinition] \| None`                                                  | `None`                             | Programmatically defined subagents                                                                                                                                                                                                                                                                      |
| `plugins`                     | `list[SdkPluginConfig]`                                                               | `[]`                               | Load custom plugins from local paths. See [Plugins](./code-agent-sdk/plugins.md) for details                                                                                                                                                                                                                  |
| `sandbox`                     | [`SandboxSettings`](#sandboxsettings) ` \| None`                                      | `None`                             | Configure sandbox behavior programmatically. See [Sandbox settings](#sandboxsettings) for details                                                                                                                                                                                                       |
| `setting_sources`             | `list[SettingSource] \| None`                                                         | `None` (CLI defaults: all sources) | Control which filesystem settings to load. Pass `[]` to disable user, project, and local settings. Managed policy settings load regardless. See [Use Claude Code features](./code-agent-sdk/claude-code-features.md#what-settingsources-does-not-control)                                                     |
| `skills`                      | `list[str] \| Literal["all"] \| None`                                                 | `None`                             | Skills available to the session. Pass `"all"` to enable every discovered skill, or a list of skill names. When set, the SDK enables the Skill tool automatically without listing it in `allowed_tools`. See [Skills](./code-agent-sdk/skills.md)                                                              |
| `max_thinking_tokens`         | `int \| None`                                                                         | `None`                             | *Deprecated* - Maximum tokens for thinking blocks. Use `thinking` instead                                                                                                                                                                                                                               |
| `thinking`                    | [`ThinkingConfig`](#thinkingconfig) ` \| None`                                        | `None`                             | Controls extended thinking behavior. Takes precedence over `max_thinking_tokens`                                                                                                                                                                                                                        |
| `effort`                      | [`EffortLevel`](#effortlevel) ` \| None`                                              | `None`                             | Effort level for thinking depth                                                                                                                                                                                                                                                                         |
| `session_store`               | [`SessionStore`](./code-agent-sdk/session-storage.md#the-sessionstore-interface) ` \| None` | `None`                             | Mirror session transcripts to an external backend so any host can resume them. See [Persist sessions to external storage](./code-agent-sdk/session-storage.md)                                                                                                                                                |
| `session_store_flush`         | `Literal["batched", "eager"]`                                                         | `"batched"`                        | When to flush mirrored transcript entries to `session_store`. `"batched"` flushes once per turn or when the buffer fills; `"eager"` triggers a background flush after every frame. Ignored when `session_store` is `None`                                                                               |

#### Handle slow or stalled API responses

The CLI subprocess reads several environment variables that control API timeouts and stall detection. Pass them through `ClaudeAgentOptions.env`:

```python theme={null}
options = ClaudeAgentOptions(
    env={
        "API_TIMEOUT_MS": "120000",
        "CLAUDE_CODE_MAX_RETRIES": "2",
        "CLAUDE_ASYNC_AGENT_STALL_TIMEOUT_MS": "120000",
    },
)
```

* `API_TIMEOUT_MS`: per-request timeout on the Anthropic client, in milliseconds. Default `600000`. Applies to the main loop and all subagents.
* `CLAUDE_CODE_MAX_RETRIES`: maximum API retries. Default `10`. Each retry gets its own `API_TIMEOUT_MS` window, so worst-case wall time is roughly `API_TIMEOUT_MS × (CLAUDE_CODE_MAX_RETRIES + 1)` plus backoff.
* `CLAUDE_ASYNC_AGENT_STALL_TIMEOUT_MS`: stall watchdog for subagents launched with `run_in_background`. Default `600000`. Resets on each stream event; on stall it aborts the subagent, marks the task failed, and surfaces the error to the parent with any partial result. Does not apply to synchronous subagents.
* `CLAUDE_ENABLE_STREAM_WATCHDOG=1` with `CLAUDE_STREAM_IDLE_TIMEOUT_MS`: aborts the request when headers have arrived but the response body stops streaming. Off by default. `CLAUDE_STREAM_IDLE_TIMEOUT_MS` defaults to `300000` and is clamped to that minimum. The aborted request goes through the normal retry path.

### `OutputFormat`

Configuration for structured output validation. Pass this as a `dict` to the `output_format` field on `ClaudeAgentOptions`:

```python theme={null}
# Expected dict shape for output_format
{
    "type": "json_schema",
    "schema": {...},  # Your JSON Schema definition
}
```

| Field    | Required | Description                                        |
| :------- | :------- | :------------------------------------------------- |
| `type`   | Yes      | Must be `"json_schema"` for JSON Schema validation |
| `schema` | Yes      | JSON Schema definition for output validation       |

### `SystemPromptPreset`

Configuration for using Claude Code's preset system prompt with optional additions.

```python theme={null}
class SystemPromptPreset(TypedDict):
    type: Literal["preset"]
    preset: Literal["claude_code"]
    append: NotRequired[str]
    exclude_dynamic_sections: NotRequired[bool]
```

| Field                      | Required | Description                                                                                                                                                                                                                                                                                                                  |
| :------------------------- | :------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `type`                     | Yes      | Must be `"preset"` to use a preset system prompt                                                                                                                                                                                                                                                                             |
| `preset`                   | Yes      | Must be `"claude_code"` to use Claude Code's system prompt                                                                                                                                                                                                                                                                   |
| `append`                   | No       | Additional instructions to append to the preset system prompt                                                                                                                                                                                                                                                                |
| `exclude_dynamic_sections` | No       | Move per-session context such as working directory, the git-repo flag, and auto-memory paths from the system prompt into the first user message. Improves prompt-cache reuse across users and machines. See [Modify system prompts](./code-agent-sdk/modifying-system-prompts.md#improve-prompt-caching-across-users-and-machines) |

### `SettingSource`

Controls which filesystem-based configuration sources the SDK loads settings from.

```python theme={null}
SettingSource = Literal["user", "project", "local"]
```

| Value       | Description                                  | Location                      |
| :---------- | :------------------------------------------- | :---------------------------- |
| `"user"`    | Global user settings                         | `~/.claude/settings.json`     |
| `"project"` | Shared project settings (version controlled) | `.claude/settings.json`       |
| `"local"`   | Local project settings (gitignored)          | `.claude/settings.local.json` |

#### Default behavior

When `setting_sources` is omitted or `None`, `query()` loads the same filesystem settings as the Claude Code CLI: user, project, and local. Managed policy settings are loaded in all cases. See [What settingSources does not control](./code-agent-sdk/claude-code-features.md#what-settingsources-does-not-control) for inputs that are read regardless of this option, and how to disable them.

#### Why use setting\_sources

**Disable filesystem settings:**

```python theme={null}
# Do not load user, project, or local settings from disk
from claude_agent_sdk import query, ClaudeAgentOptions

async for message in query(
    prompt="Analyze this code",
    options=ClaudeAgentOptions(
        setting_sources=[]
    ),
):
    print(message)
```

<Note>
  In Python SDK 0.1.59 and earlier, an empty list was treated the same as omitting the option, so `setting_sources=[]` did not disable filesystem settings. Upgrade to a newer release if you need an empty list to take effect. The TypeScript SDK is not affected.
</Note>

**Load all filesystem settings explicitly:**

```python theme={null}
from claude_agent_sdk import query, ClaudeAgentOptions

async for message in query(
    prompt="Analyze this code",
    options=ClaudeAgentOptions(
        setting_sources=["user", "project", "local"]
    ),
):
    print(message)
```

**Load only specific setting sources:**

```python theme={null}
# Load only project settings, ignore user and local
async for message in query(
    prompt="Run CI checks",
    options=ClaudeAgentOptions(
        setting_sources=["project"]  # Only .claude/settings.json
    ),
):
    print(message)
```

**Testing and CI environments:**

```python theme={null}
# Ensure consistent behavior in CI by excluding local settings
async for message in query(
    prompt="Run tests",
    options=ClaudeAgentOptions(
        setting_sources=["project"],  # Only team-shared settings
        permission_mode="bypassPermissions",
    ),
):
    print(message)
```

**SDK-only applications:**

```python theme={null}
# Define everything programmatically.
# Pass [] to opt out of filesystem setting sources.
async for message in query(
    prompt="Review this PR",
    options=ClaudeAgentOptions(
        setting_sources=[],
        agents={...},
        mcp_servers={...},
        allowed_tools=["Read", "Grep", "Glob"],
    ),
):
    print(message)
```

**Loading CLAUDE.md project instructions:**

```python theme={null}
# Load project settings to include CLAUDE.md files
async for message in query(
    prompt="Add a new feature following project conventions",
    options=ClaudeAgentOptions(
        system_prompt={
            "type": "preset",
            "preset": "claude_code",  # Use Claude Code's system prompt
        },
        setting_sources=["project"],  # Loads CLAUDE.md from project
        allowed_tools=["Read", "Write", "Edit"],
    ),
):
    print(message)
```

#### Settings precedence

When multiple sources are loaded, settings are merged with this precedence (highest to lowest):

1. Local settings (`.claude/settings.local.json`)
2. Project settings (`.claude/settings.json`)
3. User settings (`~/.claude/settings.json`)

Programmatic options such as `agents` and `allowed_tools` override user, project, and local filesystem settings. Managed policy settings take precedence over programmatic options.

### `AgentDefinition`

Configuration for a subagent defined programmatically.

```python theme={null}
@dataclass
class AgentDefinition:
    description: str
    prompt: str
    tools: list[str] | None = None
    disallowedTools: list[str] | None = None
    model: str | None = None
    skills: list[str] | None = None
    memory: Literal["user", "project", "local"] | None = None
    mcpServers: list[str | dict[str, Any]] | None = None
    initialPrompt: str | None = None
    maxTurns: int | None = None
    background: bool | None = None
    effort: EffortLevel | int | None = None
    permissionMode: PermissionMode | None = None
```

| Field             | Required | Description                                                                                                                                                  |
| :---------------- | :------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `description`     | Yes      | Natural language description of when to use this agent                                                                                                       |
| `prompt`          | Yes      | The agent's system prompt                                                                                                                                    |
| `tools`           | No       | Array of allowed tool names. If omitted, inherits all tools                                                                                                  |
| `disallowedTools` | No       | Array of tool names to remove from the agent's tool set                                                                                                      |
| `model`           | No       | Model override for this agent. Accepts an alias such as `"sonnet"`, `"opus"`, `"haiku"`, or `"inherit"`, or a full model ID. If omitted, uses the main model |
| `skills`          | No       | List of skill names to preload into the agent's context at startup. Unlisted skills remain invocable through the Skill tool                                  |
| `memory`          | No       | Memory source for this agent: `"user"`, `"project"`, or `"local"`                                                                                            |
| `mcpServers`      | No       | MCP servers available to this agent. Each entry is a server name or an inline `{name: config}` dict                                                          |
| `initialPrompt`   | No       | Auto-submitted as the first user turn when this agent runs as the main thread agent                                                                          |
| `maxTurns`        | No       | Maximum number of agentic turns before the agent stops                                                                                                       |
| `background`      | No       | Run this agent as a non-blocking background task when invoked                                                                                                |
| `effort`          | No       | Reasoning effort level for this agent. Accepts a named level or an integer. See [`EffortLevel`](#effortlevel)                                                |
| `permissionMode`  | No       | Permission mode for tool execution within this agent. See [`PermissionMode`](#permissionmode)                                                                |

<Note>
  `AgentDefinition` field names use camelCase, such as `disallowedTools`, `permissionMode`, and `maxTurns`. These names map directly to the wire format shared with the TypeScript SDK. This differs from `ClaudeAgentOptions`, which uses Python snake\_case for the equivalent top-level fields such as `disallowed_tools` and `permission_mode`. Because `AgentDefinition` is a dataclass, passing a snake\_case keyword raises a `TypeError` at construction time.
</Note>

### `PermissionMode`

Permission modes for controlling tool execution.

```python theme={null}
PermissionMode = Literal[
    "default",  # Standard permission behavior
    "acceptEdits",  # Auto-accept file edits
    "plan",  # Planning mode - read-only tools only
    "dontAsk",  # Deny anything not pre-approved instead of prompting
    "bypassPermissions",  # Bypass all permission checks (use with caution)
]
```

### `EffortLevel`

Effort levels for guiding thinking depth.

```python theme={null}
EffortLevel = Literal[
    "low",  # Minimal thinking, fastest responses
    "medium",  # Moderate thinking
    "high",  # Deep reasoning
    "xhigh",  # Extended reasoning (Opus 4.7 only; falls back to "high" on other models)
    "max",  # Maximum effort
]
```

### `CanUseTool`

Type alias for tool permission callback functions.

```python theme={null}
CanUseTool = Callable[
    [str, dict[str, Any], ToolPermissionContext], Awaitable[PermissionResult]
]
```

The callback receives:

* `tool_name`: Name of the tool being called
* `input_data`: The tool's input parameters
* `context`: A `ToolPermissionContext` with additional information

Returns a `PermissionResult` (either `PermissionResultAllow` or `PermissionResultDeny`).

### `ToolPermissionContext`

Context information passed to tool permission callbacks.

```python theme={null}
@dataclass
class ToolPermissionContext:
    signal: Any | None = None  # Future: abort signal support
    suggestions: list[PermissionUpdate] = field(default_factory=list)
    blocked_path: str | None = None
    decision_reason: str | None = None
    title: str | None = None
    display_name: str | None = None
    description: str | None = None
```

| Field             | Type                     | Description                                                                                                                                                                                                                                 |
| :---------------- | :----------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `signal`          | `Any \| None`            | Reserved for future abort signal support                                                                                                                                                                                                    |
| `suggestions`     | `list[PermissionUpdate]` | Permission update suggestions from the CLI. Bash prompts include a suggestion with the `localSettings` destination, so returning it in `updated_permissions` writes the rule to `.claude/settings.local.json` and persists across sessions. |
| `blocked_path`    | `str \| None`            | File path that triggered the permission request, when applicable. For example, when a Bash command tries to access a path outside allowed directories                                                                                       |
| `decision_reason` | `str \| None`            | Reason this permission request was triggered. Forwarded from a PreToolUse hook's `permissionDecisionReason` when the hook returned `"ask"`                                                                                                  |
| `title`           | `str \| None`            | Full permission prompt sentence, such as `Claude wants to read foo.txt`. Use as the primary prompt text when present                                                                                                                        |
| `display_name`    | `str \| None`            | Short noun phrase for the tool action, such as `Read file`, suitable for button labels                                                                                                                                                      |
| `description`     | `str \| None`            | Human-readable subtitle for the permission UI                                                                                                                                                                                               |

### `PermissionResult`

Union type for permission callback results.

```python theme={null}
PermissionResult = PermissionResultAllow | PermissionResultDeny
```

### `PermissionResultAllow`

Result indicating the tool call should be allowed.

```python theme={null}
@dataclass
class PermissionResultAllow:
    behavior: Literal["allow"] = "allow"
    updated_input: dict[str, Any] | None = None
    updated_permissions: list[PermissionUpdate] | None = None
```

| Field                 | Type                             | Default   | Description                               |
| :-------------------- | :------------------------------- | :-------- | :---------------------------------------- |
| `behavior`            | `Literal["allow"]`               | `"allow"` | Must be "allow"                           |
| `updated_input`       | `dict[str, Any] \| None`         | `None`    | Modified input to use instead of original |
| `updated_permissions` | `list[PermissionUpdate] \| None` | `None`    | Permission updates to apply               |

### `PermissionResultDeny`

Result indicating the tool call should be denied.

```python theme={null}
@dataclass
class PermissionResultDeny:
    behavior: Literal["deny"] = "deny"
    message: str = ""
    interrupt: bool = False
```

| Field       | Type              | Default  | Description                                |
| :---------- | :---------------- | :------- | :----------------------------------------- |
| `behavior`  | `Literal["deny"]` | `"deny"` | Must be "deny"                             |
| `message`   | `str`             | `""`     | Message explaining why the tool was denied |
| `interrupt` | `bool`            | `False`  | Whether to interrupt the current execution |

### `PermissionUpdate`

Configuration for updating permissions programmatically.

```python theme={null}
@dataclass
class PermissionUpdate:
    type: Literal[
        "addRules",
        "replaceRules",
        "removeRules",
        "setMode",
        "addDirectories",
        "removeDirectories",
    ]
    rules: list[PermissionRuleValue] | None = None
    behavior: Literal["allow", "deny", "ask"] | None = None
    mode: PermissionMode | None = None
    directories: list[str] | None = None
    destination: (
        Literal["userSettings", "projectSettings", "localSettings", "session"] | None
    ) = None
```

| Field         | Type                                      | Description                                     |
| :------------ | :---------------------------------------- | :---------------------------------------------- |
| `type`        | `Literal[...]`                            | The type of permission update operation         |
| `rules`       | `list[PermissionRuleValue] \| None`       | Rules for add/replace/remove operations         |
| `behavior`    | `Literal["allow", "deny", "ask"] \| None` | Behavior for rule-based operations              |
| `mode`        | `PermissionMode \| None`                  | Mode for setMode operation                      |
| `directories` | `list[str] \| None`                       | Directories for add/remove directory operations |
| `destination` | `Literal[...] \| None`                    | Where to apply the permission update            |

### `PermissionRuleValue`

A rule to add, replace, or remove in a permission update.

```python theme={null}
@dataclass
class PermissionRuleValue:
    tool_name: str
    rule_content: str | None = None
```

### `ToolsPreset`

Preset tools configuration for using Claude Code's default tool set.

```python theme={null}
class ToolsPreset(TypedDict):
    type: Literal["preset"]
    preset: Literal["claude_code"]
```

### `ThinkingConfig`

Controls extended thinking behavior. A union of three configurations:

```python theme={null}
ThinkingDisplay = Literal["summarized", "omitted"]


class ThinkingConfigAdaptive(TypedDict):
    type: Literal["adaptive"]
    display: NotRequired[ThinkingDisplay]


class ThinkingConfigEnabled(TypedDict):
    type: Literal["enabled"]
    budget_tokens: int
    display: NotRequired[ThinkingDisplay]


class ThinkingConfigDisabled(TypedDict):
    type: Literal["disabled"]


ThinkingConfig = ThinkingConfigAdaptive | ThinkingConfigEnabled | ThinkingConfigDisabled
```

| Variant    | Fields                             | Description                                  |
| :--------- | :--------------------------------- | :------------------------------------------- |
| `adaptive` | `type`, `display`                  | Claude adaptively decides when to think      |
| `enabled`  | `type`, `budget_tokens`, `display` | Enable thinking with a specific token budget |
| `disabled` | `type`                             | Disable thinking                             |

The optional `display` field controls whether thinking text is returned `"summarized"` or `"omitted"`. On Claude Opus 4.7 and later, the API default is `"omitted"`, so set `"summarized"` to receive thinking content in [`ThinkingBlock`](#thinkingblock) outputs.

Because these are `TypedDict` classes, they're plain dicts at runtime. Either construct them as dict literals or call the class like a constructor; both produce a `dict`. Access fields with `config["budget_tokens"]`, not `config.budget_tokens`:

```python theme={null}
from claude_agent_sdk import ClaudeAgentOptions, ThinkingConfigEnabled

# Option 1: dict literal (recommended, no import needed)
options = ClaudeAgentOptions(thinking={"type": "enabled", "budget_tokens": 20000})

# Option 2: constructor-style (returns a plain dict)
config = ThinkingConfigEnabled(type="enabled", budget_tokens=20000)
print(config["budget_tokens"])  # 20000
# config.budget_tokens would raise AttributeError
```

### `SdkBeta`

Literal type for SDK beta features.

```python theme={null}
SdkBeta = Literal["context-1m-2025-08-07"]
```

Use with the `betas` field in `ClaudeAgentOptions` to enable beta features.

<Warning>
  The `context-1m-2025-08-07` beta is retired as of April 30, 2026. Passing this header with Claude Sonnet 4.5 or Sonnet 4 has no effect, and requests that exceed the standard 200k-token context window return an error. To use a 1M-token context window, migrate to [Claude Sonnet 4.6, Claude Opus 4.6, or Claude Opus 4.7](https://platform.claude.com/docs/en/about-claude/models/overview), which include 1M context at standard pricing with no beta header required.
</Warning>

### `McpSdkServerConfig`

Configuration for SDK MCP servers created with `create_sdk_mcp_server()`.

```python theme={null}
class McpSdkServerConfig(TypedDict):
    type: Literal["sdk"]
    name: str
    instance: Any  # MCP Server instance
```

### `McpServerConfig`

Union type for MCP server configurations.

```python theme={null}
McpServerConfig = (
    McpStdioServerConfig | McpSSEServerConfig | McpHttpServerConfig | McpSdkServerConfig
)
```

#### `McpStdioServerConfig`

```python theme={null}
class McpStdioServerConfig(TypedDict):
    type: NotRequired[Literal["stdio"]]  # Optional for backwards compatibility
    command: str
    args: NotRequired[list[str]]
    env: NotRequired[dict[str, str]]
```

#### `McpSSEServerConfig`

```python theme={null}
class McpSSEServerConfig(TypedDict):
    type: Literal["sse"]
    url: str
    headers: NotRequired[dict[str, str]]
```

#### `McpHttpServerConfig`

```python theme={null}
class McpHttpServerConfig(TypedDict):
    type: Literal["http"]
    url: str
    headers: NotRequired[dict[str, str]]
```

### `McpServerStatusConfig`

The configuration of an MCP server as reported by [`get_mcp_status()`](#methods). This is the union of all [`McpServerConfig`](#mcpserverconfig) transport variants plus an output-only `claudeai-proxy` variant for servers proxied through claude.ai.

```python theme={null}
McpServerStatusConfig = (
    McpStdioServerConfig
    | McpSSEServerConfig
    | McpHttpServerConfig
    | McpSdkServerConfigStatus
    | McpClaudeAIProxyServerConfig
)
```

`McpSdkServerConfigStatus` is the serializable form of [`McpSdkServerConfig`](#mcpsdkserverconfig) with only `type` (`"sdk"`) and `name` (`str`) fields; the in-process `instance` is omitted. `McpClaudeAIProxyServerConfig` has `type` (`"claudeai-proxy"`), `url` (`str`), and `id` (`str`) fields.

### `McpStatusResponse`

Response from [`ClaudeSDKClient.get_mcp_status()`](#methods). Wraps the list of server statuses under the `mcpServers` key.

```python theme={null}
class McpStatusResponse(TypedDict):
    mcpServers: list[McpServerStatus]
```

### `McpServerStatus`

Status of a connected MCP server, contained in [`McpStatusResponse`](#mcpstatusresponse).

```python theme={null}
class McpServerStatus(TypedDict):
    name: str
    status: McpServerConnectionStatus  # "connected" | "failed" | "needs-auth" | "pending" | "disabled"
    serverInfo: NotRequired[McpServerInfo]
    error: NotRequired[str]
    config: NotRequired[McpServerStatusConfig]
    scope: NotRequired[str]
    tools: NotRequired[list[McpToolInfo]]
```

| Field        | Type                                                         | Description                                                                                                                                                                   |
| :----------- | :----------------------------------------------------------- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `name`       | `str`                                                        | Server name                                                                                                                                                                   |
| `status`     | `str`                                                        | One of `"connected"`, `"failed"`, `"needs-auth"`, `"pending"`, or `"disabled"`                                                                                                |
| `serverInfo` | `dict` (optional)                                            | Server name and version (`{"name": str, "version": str}`)                                                                                                                     |
| `error`      | `str` (optional)                                             | Error message if the server failed to connect                                                                                                                                 |
| `config`     | [`McpServerStatusConfig`](#mcpserverstatusconfig) (optional) | Server configuration. Same shape as [`McpServerConfig`](#mcpserverconfig) (stdio, SSE, HTTP, or SDK), plus a `claudeai-proxy` variant for servers connected through claude.ai |
| `scope`      | `str` (optional)                                             | Configuration scope                                                                                                                                                           |
| `tools`      | `list` (optional)                                            | Tools provided by this server, each with `name`, `description`, and `annotations` fields                                                                                      |

### `SdkPluginConfig`

Configuration for loading plugins in the SDK.

```python theme={null}
class SdkPluginConfig(TypedDict):
    type: Literal["local"]
    path: str
```

| Field  | Type               | Description                                                |
| :----- | :----------------- | :--------------------------------------------------------- |
| `type` | `Literal["local"]` | Must be `"local"` (only local plugins currently supported) |
| `path` | `str`              | Absolute or relative path to the plugin directory          |

**Example:**

```python theme={null}
plugins = [
    {"type": "local", "path": "./my-plugin"},
    {"type": "local", "path": "/absolute/path/to/plugin"},
]
```

For complete information on creating and using plugins, see [Plugins](./code-agent-sdk/plugins.md).

## Message Types

### `Message`

Union type of all possible messages.

```python theme={null}
Message = (
    UserMessage
    | AssistantMessage
    | SystemMessage
    | ResultMessage
    | StreamEvent
    | RateLimitEvent
)
```

### `UserMessage`

User input message.

```python theme={null}
@dataclass
class UserMessage:
    content: str | list[ContentBlock]
    uuid: str | None = None
    parent_tool_use_id: str | None = None
    tool_use_result: dict[str, Any] | None = None
```

| Field                | Type                        | Description                                           |
| :------------------- | :-------------------------- | :---------------------------------------------------- |
| `content`            | `str \| list[ContentBlock]` | Message content as text or content blocks             |
| `uuid`               | `str \| None`               | Unique message identifier                             |
| `parent_tool_use_id` | `str \| None`               | Tool use ID if this message is a tool result response |
| `tool_use_result`    | `dict[str, Any] \| None`    | Tool result data if applicable                        |

### `AssistantMessage`

Assistant response message with content blocks.

```python theme={null}
@dataclass
class AssistantMessage:
    content: list[ContentBlock]
    model: str
    parent_tool_use_id: str | None = None
    error: AssistantMessageError | None = None
    usage: dict[str, Any] | None = None
    message_id: str | None = None
```

| Field                | Type                                                         | Description                                                                    |
| :------------------- | :----------------------------------------------------------- | :----------------------------------------------------------------------------- |
| `content`            | `list[ContentBlock]`                                         | List of content blocks in the response                                         |
| `model`              | `str`                                                        | Model that generated the response                                              |
| `parent_tool_use_id` | `str \| None`                                                | Tool use ID if this is a nested response                                       |
| `error`              | [`AssistantMessageError`](#assistantmessageerror) ` \| None` | Error type if the response encountered an error                                |
| `usage`              | `dict[str, Any] \| None`                                     | Per-message token usage (same keys as [`ResultMessage.usage`](#resultmessage)) |
| `message_id`         | `str \| None`                                                | API message ID. Multiple messages from one turn share the same ID              |

### `AssistantMessageError`

Possible error types for assistant messages.

```python theme={null}
AssistantMessageError = Literal[
    "authentication_failed",
    "billing_error",
    "rate_limit",
    "invalid_request",
    "server_error",
    "max_output_tokens",
    "unknown",
]
```

### `SystemMessage`

System message with metadata.

```python theme={null}
@dataclass
class SystemMessage:
    subtype: str
    data: dict[str, Any]
```

### `ResultMessage`

Final result message with cost and usage information.

```python theme={null}
@dataclass
class ResultMessage:
    subtype: str
    duration_ms: int
    duration_api_ms: int
    is_error: bool
    num_turns: int
    session_id: str
    stop_reason: str | None = None
    total_cost_usd: float | None = None
    usage: dict[str, Any] | None = None
    result: str | None = None
    structured_output: Any = None
    model_usage: dict[str, Any] | None = None
    permission_denials: list[Any] | None = None
    deferred_tool_use: DeferredToolUse | None = None
    errors: list[str] | None = None
    api_error_status: int | None = None
    uuid: str | None = None
```

The `usage` dict contains the following keys when present:

| Key                           | Type  | Description                              |
| ----------------------------- | ----- | ---------------------------------------- |
| `input_tokens`                | `int` | Total input tokens consumed.             |
| `output_tokens`               | `int` | Total output tokens generated.           |
| `cache_creation_input_tokens` | `int` | Tokens used to create new cache entries. |
| `cache_read_input_tokens`     | `int` | Tokens read from existing cache entries. |

The `model_usage` dict maps model names to per-model usage. The inner dict keys use camelCase because the value is passed through unmodified from the underlying CLI process, matching the TypeScript [`ModelUsage`](./code-agent-sdk/typescript.md#modelusage) type:

| Key                        | Type    | Description                                                                                                                              |
| -------------------------- | ------- | ---------------------------------------------------------------------------------------------------------------------------------------- |
| `inputTokens`              | `int`   | Input tokens for this model.                                                                                                             |
| `outputTokens`             | `int`   | Output tokens for this model.                                                                                                            |
| `cacheReadInputTokens`     | `int`   | Cache read tokens for this model.                                                                                                        |
| `cacheCreationInputTokens` | `int`   | Cache creation tokens for this model.                                                                                                    |
| `webSearchRequests`        | `int`   | Web search requests made by this model.                                                                                                  |
| `costUSD`                  | `float` | Estimated cost in USD for this model, computed client-side. See [Track cost and usage](./code-agent-sdk/cost-tracking.md) for billing caveats. |
| `contextWindow`            | `int`   | Context window size for this model.                                                                                                      |
| `maxOutputTokens`          | `int`   | Maximum output token limit for this model.                                                                                               |

### `StreamEvent`

Stream event for partial message updates during streaming. Only received when `include_partial_messages=True` in `ClaudeAgentOptions`. Import via `from claude_agent_sdk.types import StreamEvent`.

```python theme={null}
@dataclass
class StreamEvent:
    uuid: str
    session_id: str
    event: dict[str, Any]  # The raw Claude API stream event
    parent_tool_use_id: str | None = None
```

| Field                | Type             | Description                                         |
| :------------------- | :--------------- | :-------------------------------------------------- |
| `uuid`               | `str`            | Unique identifier for this event                    |
| `session_id`         | `str`            | Session identifier                                  |
| `event`              | `dict[str, Any]` | The raw Claude API stream event data                |
| `parent_tool_use_id` | `str \| None`    | Parent tool use ID if this event is from a subagent |

### `RateLimitEvent`

Emitted when rate limit status changes (for example, from `"allowed"` to `"allowed_warning"`). Use this to warn users before they hit a hard limit, or to back off when status is `"rejected"`.

```python theme={null}
@dataclass
class RateLimitEvent:
    rate_limit_info: RateLimitInfo
    uuid: str
    session_id: str
```

| Field             | Type                              | Description              |
| :---------------- | :-------------------------------- | :----------------------- |
| `rate_limit_info` | [`RateLimitInfo`](#ratelimitinfo) | Current rate limit state |
| `uuid`            | `str`                             | Unique event identifier  |
| `session_id`      | `str`                             | Session identifier       |

### `RateLimitInfo`

Rate limit state carried by [`RateLimitEvent`](#ratelimitevent).

```python theme={null}
RateLimitStatus = Literal["allowed", "allowed_warning", "rejected"]
RateLimitType = Literal[
    "five_hour", "seven_day", "seven_day_opus", "seven_day_sonnet", "overage"
]


@dataclass
class RateLimitInfo:
    status: RateLimitStatus
    resets_at: int | None = None
    rate_limit_type: RateLimitType | None = None
    utilization: float | None = None
    overage_status: RateLimitStatus | None = None
    overage_resets_at: int | None = None
    overage_disabled_reason: str | None = None
    raw: dict[str, Any] = field(default_factory=dict)
```

| Field                     | Type                      | Description                                                                                           |
| :------------------------ | :------------------------ | :---------------------------------------------------------------------------------------------------- |
| `status`                  | `RateLimitStatus`         | Current status. `"allowed_warning"` means approaching the limit; `"rejected"` means the limit was hit |
| `resets_at`               | `int \| None`             | Unix timestamp when the rate limit window resets                                                      |
| `rate_limit_type`         | `RateLimitType \| None`   | Which rate limit window applies                                                                       |
| `utilization`             | `float \| None`           | Fraction of the rate limit consumed (0.0 to 1.0)                                                      |
| `overage_status`          | `RateLimitStatus \| None` | Status of pay-as-you-go overage usage, if applicable                                                  |
| `overage_resets_at`       | `int \| None`             | Unix timestamp when the overage window resets                                                         |
| `overage_disabled_reason` | `str \| None`             | Why overage is unavailable, if status is `"rejected"`                                                 |
| `raw`                     | `dict[str, Any]`          | Full raw dict from the CLI, including fields not modeled above                                        |

### `TaskStartedMessage`

Emitted when a background task starts. A background task is anything tracked outside the main turn: a backgrounded Bash command, a [Monitor](#monitor) watch, a subagent spawned via the Agent tool, or a remote agent. The `task_type` field tells you which. This naming is unrelated to the `Task`-to-`Agent` tool rename.

```python theme={null}
@dataclass
class TaskStartedMessage(SystemMessage):
    task_id: str
    description: str
    uuid: str
    session_id: str
    tool_use_id: str | None = None
    task_type: str | None = None
```

| Field         | Type          | Description                                                                                                                 |
| :------------ | :------------ | :-------------------------------------------------------------------------------------------------------------------------- |
| `task_id`     | `str`         | Unique identifier for the task                                                                                              |
| `description` | `str`         | Description of the task                                                                                                     |
| `uuid`        | `str`         | Unique message identifier                                                                                                   |
| `session_id`  | `str`         | Session identifier                                                                                                          |
| `tool_use_id` | `str \| None` | Associated tool use ID                                                                                                      |
| `task_type`   | `str \| None` | Which kind of background task: `"local_bash"` for background Bash and Monitor watches, `"local_agent"`, or `"remote_agent"` |

### `TaskUsage`

Token and timing data for a background task.

```python theme={null}
class TaskUsage(TypedDict):
    total_tokens: int
    tool_uses: int
    duration_ms: int
```

### `TaskProgressMessage`

Emitted periodically with progress updates for a running background task.

```python theme={null}
@dataclass
class TaskProgressMessage(SystemMessage):
    task_id: str
    description: str
    usage: TaskUsage
    uuid: str
    session_id: str
    tool_use_id: str | None = None
    last_tool_name: str | None = None
```

| Field            | Type          | Description                         |
| :--------------- | :------------ | :---------------------------------- |
| `task_id`        | `str`         | Unique identifier for the task      |
| `description`    | `str`         | Current status description          |
| `usage`          | `TaskUsage`   | Token usage for this task so far    |
| `uuid`           | `str`         | Unique message identifier           |
| `session_id`     | `str`         | Session identifier                  |
| `tool_use_id`    | `str \| None` | Associated tool use ID              |
| `last_tool_name` | `str \| None` | Name of the last tool the task used |

### `TaskNotificationMessage`

Emitted when a background task completes, fails, or is stopped. Background tasks include `run_in_background` Bash commands, Monitor watches, and background subagents.

```python theme={null}
@dataclass
class TaskNotificationMessage(SystemMessage):
    task_id: str
    status: TaskNotificationStatus  # "completed" | "failed" | "stopped"
    output_file: str
    summary: str
    uuid: str
    session_id: str
    tool_use_id: str | None = None
    usage: TaskUsage | None = None
```

| Field         | Type                     | Description                                      |
| :------------ | :----------------------- | :----------------------------------------------- |
| `task_id`     | `str`                    | Unique identifier for the task                   |
| `status`      | `TaskNotificationStatus` | One of `"completed"`, `"failed"`, or `"stopped"` |
| `output_file` | `str`                    | Path to the task output file                     |
| `summary`     | `str`                    | Summary of the task result                       |
| `uuid`        | `str`                    | Unique message identifier                        |
| `session_id`  | `str`                    | Session identifier                               |
| `tool_use_id` | `str \| None`            | Associated tool use ID                           |
| `usage`       | `TaskUsage \| None`      | Final token usage for the task                   |

## Content Block Types

### `ContentBlock`

Union type of all content blocks.

```python theme={null}
ContentBlock = TextBlock | ThinkingBlock | ToolUseBlock | ToolResultBlock
```

### `TextBlock`

Text content block.

```python theme={null}
@dataclass
class TextBlock:
    text: str
```

### `ThinkingBlock`

Thinking content block (for models with thinking capability).

```python theme={null}
@dataclass
class ThinkingBlock:
    thinking: str
    signature: str
```

### `ToolUseBlock`

Tool use request block.

```python theme={null}
@dataclass
class ToolUseBlock:
    id: str
    name: str
    input: dict[str, Any]
```

### `ToolResultBlock`

Tool execution result block.

```python theme={null}
@dataclass
class ToolResultBlock:
    tool_use_id: str
    content: str | list[dict[str, Any]] | None = None
    is_error: bool | None = None
```

## Error Types

### `ClaudeSDKError`

Base exception class for all SDK errors.

```python theme={null}
class ClaudeSDKError(Exception):
    """Base error for Claude SDK."""
```

### `CLINotFoundError`

Raised when Claude Code CLI is not installed or not found.

```python theme={null}
class CLINotFoundError(CLIConnectionError):
    def __init__(
        self, message: str = "Claude Code not found", cli_path: str | None = None
    ):
        """
        Args:
            message: Error message (default: "Claude Code not found")
            cli_path: Optional path to the CLI that was not found
        """
```

### `CLIConnectionError`

Raised when connection to Claude Code fails.

```python theme={null}
class CLIConnectionError(ClaudeSDKError):
    """Failed to connect to Claude Code."""
```

### `ProcessError`

Raised when the Claude Code process fails.

```python theme={null}
class ProcessError(ClaudeSDKError):
    def __init__(
        self, message: str, exit_code: int | None = None, stderr: str | None = None
    ):
        self.exit_code = exit_code
        self.stderr = stderr
```

### `CLIJSONDecodeError`

Raised when JSON parsing fails.

```python theme={null}
class CLIJSONDecodeError(ClaudeSDKError):
    def __init__(self, line: str, original_error: Exception):
        """
        Args:
            line: The line that failed to parse
            original_error: The original JSON decode exception
        """
        self.line = line
        self.original_error = original_error
```

## Hook Types

For a comprehensive guide on using hooks with examples and common patterns, see the [Hooks guide](./code-agent-sdk/hooks.md).

### `HookEvent`

Supported hook event types.

```python theme={null}
HookEvent = Literal[
    "PreToolUse",  # Called before tool execution
    "PostToolUse",  # Called after tool execution
    "PostToolUseFailure",  # Called when a tool execution fails
    "UserPromptSubmit",  # Called when user submits a prompt
    "Stop",  # Called when stopping execution
    "SubagentStop",  # Called when a subagent stops
    "PreCompact",  # Called before message compaction
    "Notification",  # Called for notification events
    "SubagentStart",  # Called when a subagent starts
    "PermissionRequest",  # Called when a permission decision is needed
]
```

<Note>
  The TypeScript SDK supports additional hook events not yet available in Python: `SessionStart`, `SessionEnd`, `Setup`, `TeammateIdle`, `TaskCompleted`, `ConfigChange`, `WorktreeCreate`, `WorktreeRemove`, and `PostToolBatch`.
</Note>

### `HookCallback`

Type definition for hook callback functions.

```python theme={null}
HookCallback = Callable[[HookInput, str | None, HookContext], Awaitable[HookJSONOutput]]
```

Parameters:

* `input`: Strongly-typed hook input with discriminated unions based on `hook_event_name` (see [`HookInput`](#hookinput))
* `tool_use_id`: Optional tool use identifier (for tool-related hooks)
* `context`: Hook context with additional information

Returns a [`HookJSONOutput`](#hookjsonoutput) that may contain:

* `decision`: `"block"` to block the action
* `systemMessage`: warning message shown to the user
* `hookSpecificOutput`: Hook-specific output data

### `HookContext`

Context information passed to hook callbacks.

```python theme={null}
class HookContext(TypedDict):
    signal: Any | None  # Future: abort signal support
```

### `HookMatcher`

Configuration for matching hooks to specific events or tools.

```python theme={null}
@dataclass
class HookMatcher:
    matcher: str | None = (
        None  # Tool name or pattern to match (e.g., "Bash", "Write|Edit")
    )
    hooks: list[HookCallback] = field(
        default_factory=list
    )  # List of callbacks to execute
    timeout: float | None = (
        None  # Timeout in seconds for all hooks in this matcher (default: 60)
    )
```

### `HookInput`

Union type of all hook input types. The actual type depends on the `hook_event_name` field.

```python theme={null}
HookInput = (
    PreToolUseHookInput
    | PostToolUseHookInput
    | PostToolUseFailureHookInput
    | UserPromptSubmitHookInput
    | StopHookInput
    | SubagentStopHookInput
    | PreCompactHookInput
    | NotificationHookInput
    | SubagentStartHookInput
    | PermissionRequestHookInput
)
```

### `BaseHookInput`

Base fields present in all hook input types.

```python theme={null}
class BaseHookInput(TypedDict):
    session_id: str
    transcript_path: str
    cwd: str
    permission_mode: NotRequired[str]
```

| Field             | Type             | Description                         |
| :---------------- | :--------------- | :---------------------------------- |
| `session_id`      | `str`            | Current session identifier          |
| `transcript_path` | `str`            | Path to the session transcript file |
| `cwd`             | `str`            | Current working directory           |
| `permission_mode` | `str` (optional) | Current permission mode             |

### `PreToolUseHookInput`

Input data for `PreToolUse` hook events.

```python theme={null}
class PreToolUseHookInput(BaseHookInput):
    hook_event_name: Literal["PreToolUse"]
    tool_name: str
    tool_input: dict[str, Any]
    tool_use_id: str
    agent_id: NotRequired[str]
    agent_type: NotRequired[str]
```

| Field             | Type                    | Description                                                        |
| :---------------- | :---------------------- | :----------------------------------------------------------------- |
| `hook_event_name` | `Literal["PreToolUse"]` | Always "PreToolUse"                                                |
| `tool_name`       | `str`                   | Name of the tool about to be executed                              |
| `tool_input`      | `dict[str, Any]`        | Input parameters for the tool                                      |
| `tool_use_id`     | `str`                   | Unique identifier for this tool use                                |
| `agent_id`        | `str` (optional)        | Subagent identifier, present when the hook fires inside a subagent |
| `agent_type`      | `str` (optional)        | Subagent type, present when the hook fires inside a subagent       |

### `PostToolUseHookInput`

Input data for `PostToolUse` hook events.

```python theme={null}
class PostToolUseHookInput(BaseHookInput):
    hook_event_name: Literal["PostToolUse"]
    tool_name: str
    tool_input: dict[str, Any]
    tool_response: Any
    tool_use_id: str
    agent_id: NotRequired[str]
    agent_type: NotRequired[str]
```

| Field             | Type                     | Description                                                        |
| :---------------- | :----------------------- | :----------------------------------------------------------------- |
| `hook_event_name` | `Literal["PostToolUse"]` | Always "PostToolUse"                                               |
| `tool_name`       | `str`                    | Name of the tool that was executed                                 |
| `tool_input`      | `dict[str, Any]`         | Input parameters that were used                                    |
| `tool_response`   | `Any`                    | Response from the tool execution                                   |
| `tool_use_id`     | `str`                    | Unique identifier for this tool use                                |
| `agent_id`        | `str` (optional)         | Subagent identifier, present when the hook fires inside a subagent |
| `agent_type`      | `str` (optional)         | Subagent type, present when the hook fires inside a subagent       |

### `PostToolUseFailureHookInput`

Input data for `PostToolUseFailure` hook events. Called when a tool execution fails.

```python theme={null}
class PostToolUseFailureHookInput(BaseHookInput):
    hook_event_name: Literal["PostToolUseFailure"]
    tool_name: str
    tool_input: dict[str, Any]
    tool_use_id: str
    error: str
    is_interrupt: NotRequired[bool]
    agent_id: NotRequired[str]
    agent_type: NotRequired[str]
```

| Field             | Type                            | Description                                                        |
| :---------------- | :------------------------------ | :----------------------------------------------------------------- |
| `hook_event_name` | `Literal["PostToolUseFailure"]` | Always "PostToolUseFailure"                                        |
| `tool_name`       | `str`                           | Name of the tool that failed                                       |
| `tool_input`      | `dict[str, Any]`                | Input parameters that were used                                    |
| `tool_use_id`     | `str`                           | Unique identifier for this tool use                                |
| `error`           | `str`                           | Error message from the failed execution                            |
| `is_interrupt`    | `bool` (optional)               | Whether the failure was caused by an interrupt                     |
| `agent_id`        | `str` (optional)                | Subagent identifier, present when the hook fires inside a subagent |
| `agent_type`      | `str` (optional)                | Subagent type, present when the hook fires inside a subagent       |

### `UserPromptSubmitHookInput`

Input data for `UserPromptSubmit` hook events.

```python theme={null}
class UserPromptSubmitHookInput(BaseHookInput):
    hook_event_name: Literal["UserPromptSubmit"]
    prompt: str
```

| Field             | Type                          | Description                 |
| :---------------- | :---------------------------- | :-------------------------- |
| `hook_event_name` | `Literal["UserPromptSubmit"]` | Always "UserPromptSubmit"   |
| `prompt`          | `str`                         | The user's submitted prompt |

### `StopHookInput`

Input data for `Stop` hook events.

```python theme={null}
class StopHookInput(BaseHookInput):
    hook_event_name: Literal["Stop"]
    stop_hook_active: bool
```

| Field              | Type              | Description                     |
| :----------------- | :---------------- | :------------------------------ |
| `hook_event_name`  | `Literal["Stop"]` | Always "Stop"                   |
| `stop_hook_active` | `bool`            | Whether the stop hook is active |

### `SubagentStopHookInput`

Input data for `SubagentStop` hook events.

```python theme={null}
class SubagentStopHookInput(BaseHookInput):
    hook_event_name: Literal["SubagentStop"]
    stop_hook_active: bool
    agent_id: str
    agent_transcript_path: str
    agent_type: str
```

| Field                   | Type                      | Description                            |
| :---------------------- | :------------------------ | :------------------------------------- |
| `hook_event_name`       | `Literal["SubagentStop"]` | Always "SubagentStop"                  |
| `stop_hook_active`      | `bool`                    | Whether the stop hook is active        |
| `agent_id`              | `str`                     | Unique identifier for the subagent     |
| `agent_transcript_path` | `str`                     | Path to the subagent's transcript file |
| `agent_type`            | `str`                     | Type of the subagent                   |

### `PreCompactHookInput`

Input data for `PreCompact` hook events.

```python theme={null}
class PreCompactHookInput(BaseHookInput):
    hook_event_name: Literal["PreCompact"]
    trigger: Literal["manual", "auto"]
    custom_instructions: str | None
```

| Field                 | Type                        | Description                        |
| :-------------------- | :-------------------------- | :--------------------------------- |
| `hook_event_name`     | `Literal["PreCompact"]`     | Always "PreCompact"                |
| `trigger`             | `Literal["manual", "auto"]` | What triggered the compaction      |
| `custom_instructions` | `str \| None`               | Custom instructions for compaction |

### `NotificationHookInput`

Input data for `Notification` hook events.

```python theme={null}
class NotificationHookInput(BaseHookInput):
    hook_event_name: Literal["Notification"]
    message: str
    title: NotRequired[str]
    notification_type: str
```

| Field               | Type                      | Description                  |
| :------------------ | :------------------------ | :--------------------------- |
| `hook_event_name`   | `Literal["Notification"]` | Always "Notification"        |
| `message`           | `str`                     | Notification message content |
| `title`             | `str` (optional)          | Notification title           |
| `notification_type` | `str`                     | Type of notification         |

### `SubagentStartHookInput`

Input data for `SubagentStart` hook events.

```python theme={null}
class SubagentStartHookInput(BaseHookInput):
    hook_event_name: Literal["SubagentStart"]
    agent_id: str
    agent_type: str
```

| Field             | Type                       | Description                        |
| :---------------- | :------------------------- | :--------------------------------- |
| `hook_event_name` | `Literal["SubagentStart"]` | Always "SubagentStart"             |
| `agent_id`        | `str`                      | Unique identifier for the subagent |
| `agent_type`      | `str`                      | Type of the subagent               |

### `PermissionRequestHookInput`

Input data for `PermissionRequest` hook events. Allows hooks to handle permission decisions programmatically.

```python theme={null}
class PermissionRequestHookInput(BaseHookInput):
    hook_event_name: Literal["PermissionRequest"]
    tool_name: str
    tool_input: dict[str, Any]
    permission_suggestions: NotRequired[list[Any]]
```

| Field                    | Type                           | Description                               |
| :----------------------- | :----------------------------- | :---------------------------------------- |
| `hook_event_name`        | `Literal["PermissionRequest"]` | Always "PermissionRequest"                |
| `tool_name`              | `str`                          | Name of the tool requesting permission    |
| `tool_input`             | `dict[str, Any]`               | Input parameters for the tool             |
| `permission_suggestions` | `list[Any]` (optional)         | Suggested permission updates from the CLI |

### `HookJSONOutput`

Union type for hook callback return values.

```python theme={null}
HookJSONOutput = AsyncHookJSONOutput | SyncHookJSONOutput
```

#### `SyncHookJSONOutput`

Synchronous hook output with control and decision fields.

```python theme={null}
class SyncHookJSONOutput(TypedDict):
    # Control fields
    continue_: NotRequired[bool]  # Whether to proceed (default: True)
    suppressOutput: NotRequired[bool]  # Hide stdout from transcript
    stopReason: NotRequired[str]  # Message when continue is False

    # Decision fields
    decision: NotRequired[Literal["block"]]
    systemMessage: NotRequired[str]  # Warning message for user
    reason: NotRequired[str]  # Feedback for Claude

    # Hook-specific output
    hookSpecificOutput: NotRequired[HookSpecificOutput]
```

<Note>
  Use `continue_` (with underscore) in Python code. It is automatically converted to `continue` when sent to the CLI.
</Note>

#### `HookSpecificOutput`

A `TypedDict` containing the hook event name and event-specific fields. The shape depends on the `hookEventName` value. For full details on available fields per hook event, see [Control execution with hooks](./code-agent-sdk/hooks.md#outputs).

A discriminated union of event-specific output types. The `hookEventName` field determines which fields are valid.

```python theme={null}
class PreToolUseHookSpecificOutput(TypedDict):
    hookEventName: Literal["PreToolUse"]
    permissionDecision: NotRequired[Literal["allow", "deny", "ask", "defer"]]
    permissionDecisionReason: NotRequired[str]
    updatedInput: NotRequired[dict[str, Any]]
    additionalContext: NotRequired[str]


class PostToolUseHookSpecificOutput(TypedDict):
    hookEventName: Literal["PostToolUse"]
    additionalContext: NotRequired[str]
    updatedToolOutput: NotRequired[Any]
    updatedMCPToolOutput: NotRequired[Any]  # Deprecated: use updatedToolOutput, which works for all tools


class PostToolUseFailureHookSpecificOutput(TypedDict):
    hookEventName: Literal["PostToolUseFailure"]
    additionalContext: NotRequired[str]


class UserPromptSubmitHookSpecificOutput(TypedDict):
    hookEventName: Literal["UserPromptSubmit"]
    additionalContext: NotRequired[str]


class NotificationHookSpecificOutput(TypedDict):
    hookEventName: Literal["Notification"]
    additionalContext: NotRequired[str]


class SubagentStartHookSpecificOutput(TypedDict):
    hookEventName: Literal["SubagentStart"]
    additionalContext: NotRequired[str]


class PermissionRequestHookSpecificOutput(TypedDict):
    hookEventName: Literal["PermissionRequest"]
    decision: dict[str, Any]


HookSpecificOutput = (
    PreToolUseHookSpecificOutput
    | PostToolUseHookSpecificOutput
    | PostToolUseFailureHookSpecificOutput
    | UserPromptSubmitHookSpecificOutput
    | NotificationHookSpecificOutput
    | SubagentStartHookSpecificOutput
    | PermissionRequestHookSpecificOutput
)
```

#### `AsyncHookJSONOutput`

Async hook output that defers hook execution.

```python theme={null}
class AsyncHookJSONOutput(TypedDict):
    async_: Literal[True]  # Set to True to defer execution
    asyncTimeout: NotRequired[int]  # Timeout in milliseconds
```

<Note>
  Use `async_` (with underscore) in Python code. It is automatically converted to `async` when sent to the CLI.
</Note>

### Hook Usage Example

This example registers two hooks: one that blocks dangerous bash commands like `rm -rf /`, and another that logs all tool usage for auditing. The security hook only runs on Bash commands (via the `matcher`), while the logging hook runs on all tools.

```python theme={null}
from claude_agent_sdk import query, ClaudeAgentOptions, HookMatcher, HookContext
from typing import Any


async def validate_bash_command(
    input_data: dict[str, Any], tool_use_id: str | None, context: HookContext
) -> dict[str, Any]:
    """Validate and potentially block dangerous bash commands."""
    if input_data["tool_name"] == "Bash":
        command = input_data["tool_input"].get("command", "")
        if "rm -rf /" in command:
            return {
                "hookSpecificOutput": {
                    "hookEventName": "PreToolUse",
                    "permissionDecision": "deny",
                    "permissionDecisionReason": "Dangerous command blocked",
                }
            }
    return {}


async def log_tool_use(
    input_data: dict[str, Any], tool_use_id: str | None, context: HookContext
) -> dict[str, Any]:
    """Log all tool usage for auditing."""
    print(f"Tool used: {input_data.get('tool_name')}")
    return {}


options = ClaudeAgentOptions(
    hooks={
        "PreToolUse": [
            HookMatcher(
                matcher="Bash", hooks=[validate_bash_command], timeout=120
            ),  # 2 min for validation
            HookMatcher(
                hooks=[log_tool_use]
            ),  # Applies to all tools (default 60s timeout)
        ],
        "PostToolUse": [HookMatcher(hooks=[log_tool_use])],
    }
)

async for message in query(prompt="Analyze this codebase", options=options):
    print(message)
```

## Tool Input/Output Types

Documentation of input/output schemas for all built-in Claude Code tools. While the Python SDK doesn't export these as types, they represent the structure of tool inputs and outputs in messages.

### Agent

**Tool name:** `Agent` (previously `Task`, which is still accepted as an alias)

**Input:**

```python theme={null}
{
    "description": str,  # A short (3-5 word) description of the task
    "prompt": str,  # The task for the agent to perform
    "subagent_type": str,  # The type of specialized agent to use
}
```

**Output:**

```python theme={null}
{
    "result": str,  # Final result from the subagent
    "usage": dict | None,  # Token usage statistics
    "total_cost_usd": float | None,  # Estimated total cost in USD
    "duration_ms": int | None,  # Execution duration in milliseconds
}
```

### AskUserQuestion

**Tool name:** `AskUserQuestion`

Asks the user clarifying questions during execution. See [Handle approvals and user input](./code-agent-sdk/user-input.md#handle-clarifying-questions) for usage details.

**Input:**

```python theme={null}
{
    "questions": [  # Questions to ask the user (1-4 questions)
        {
            "question": str,  # The complete question to ask the user
            "header": str,  # Very short label displayed as a chip/tag (max 12 chars)
            "options": [  # The available choices (2-4 options)
                {
                    "label": str,  # Display text for this option (1-5 words)
                    "description": str,  # Explanation of what this option means
                }
            ],
            "multiSelect": bool,  # Set to true to allow multiple selections
        }
    ],
    "answers": dict[str, str | list[str]] | None,
    # User answers populated by the permission system. Multi-select
    # answers may be a list of labels or a comma-joined string
}
```

**Output:**

```python theme={null}
{
    "questions": [  # The questions that were asked
        {
            "question": str,
            "header": str,
            "options": [{"label": str, "description": str}],
            "multiSelect": bool,
        }
    ],
    "answers": dict[str, str],  # Maps question text to answer string
    # Multi-select answers are comma-separated
}
```

### Bash

**Tool name:** `Bash`

**Input:**

```python theme={null}
{
    "command": str,  # The command to execute
    "timeout": int | None,  # Optional timeout in milliseconds (max 600000)
    "description": str | None,  # Clear, concise description (5-10 words)
    "run_in_background": bool | None,  # Set to true to run in background
}
```

**Output:**

```python theme={null}
{
    "output": str,  # Combined stdout and stderr output
    "exitCode": int,  # Exit code of the command
    "killed": bool | None,  # Whether command was killed due to timeout
    "shellId": str | None,  # Shell ID for background processes
}
```

### Monitor

**Tool name:** `Monitor`

Runs a background script and delivers each stdout line to Claude as an event so it can react without polling. Monitor follows the same permission rules as Bash. See the [Monitor tool reference](./code-tools-reference.md#monitor-tool) for behavior and provider availability.

**Input:**

```python theme={null}
{
    "command": str,  # Shell script; each stdout line is an event, exit ends the watch
    "description": str,  # Short description shown in notifications
    "timeout_ms": int | None,  # Kill after this deadline (default 300000, max 3600000)
    "persistent": bool | None,  # Run for the lifetime of the session; stop with TaskStop
}
```

**Output:**

```python theme={null}
{
    "taskId": str,  # ID of the background monitor task
    "timeoutMs": int,  # Timeout deadline in milliseconds (0 when persistent)
    "persistent": bool | None,  # True when running until TaskStop or session end
}
```

### Edit

**Tool name:** `Edit`

**Input:**

```python theme={null}
{
    "file_path": str,  # The absolute path to the file to modify
    "old_string": str,  # The text to replace
    "new_string": str,  # The text to replace it with
    "replace_all": bool | None,  # Replace all occurrences (default False)
}
```

**Output:**

```python theme={null}
{
    "message": str,  # Confirmation message
    "replacements": int,  # Number of replacements made
    "file_path": str,  # File path that was edited
}
```

### Read

**Tool name:** `Read`

**Input:**

```python theme={null}
{
    "file_path": str,  # The absolute path to the file to read
    "offset": int | None,  # The line number to start reading from
    "limit": int | None,  # The number of lines to read
}
```

**Output (Text files):**

```python theme={null}
{
    "content": str,  # File contents with line numbers
    "total_lines": int,  # Total number of lines in file
    "lines_returned": int,  # Lines actually returned
}
```

**Output (Images):**

```python theme={null}
{
    "image": str,  # Base64 encoded image data
    "mime_type": str,  # Image MIME type
    "file_size": int,  # File size in bytes
}
```

### Write

**Tool name:** `Write`

**Input:**

```python theme={null}
{
    "file_path": str,  # The absolute path to the file to write
    "content": str,  # The content to write to the file
}
```

**Output:**

```python theme={null}
{
    "message": str,  # Success message
    "bytes_written": int,  # Number of bytes written
    "file_path": str,  # File path that was written
}
```

### Glob

**Tool name:** `Glob`

**Input:**

```python theme={null}
{
    "pattern": str,  # The glob pattern to match files against
    "path": str | None,  # The directory to search in (defaults to cwd)
}
```

**Output:**

```python theme={null}
{
    "matches": list[str],  # Array of matching file paths
    "count": int,  # Number of matches found
    "search_path": str,  # Search directory used
}
```

### Grep

**Tool name:** `Grep`

**Input:**

```python theme={null}
{
    "pattern": str,  # The regular expression pattern
    "path": str | None,  # File or directory to search in
    "glob": str | None,  # Glob pattern to filter files
    "type": str | None,  # File type to search
    "output_mode": str | None,  # "content", "files_with_matches", or "count"
    "-i": bool | None,  # Case insensitive search
    "-n": bool | None,  # Show line numbers
    "-B": int | None,  # Lines to show before each match
    "-A": int | None,  # Lines to show after each match
    "-C": int | None,  # Lines to show before and after
    "head_limit": int | None,  # Limit output to first N lines/entries
    "multiline": bool | None,  # Enable multiline mode
}
```

**Output (content mode):**

```python theme={null}
{
    "matches": [
        {
            "file": str,
            "line_number": int | None,
            "line": str,
            "before_context": list[str] | None,
            "after_context": list[str] | None,
        }
    ],
    "total_matches": int,
}
```

**Output (files\_with\_matches mode):**

```python theme={null}
{
    "files": list[str],  # Files containing matches
    "count": int,  # Number of files with matches
}
```

### NotebookEdit

**Tool name:** `NotebookEdit`

**Input:**

```python theme={null}
{
    "notebook_path": str,  # Absolute path to the Jupyter notebook
    "cell_id": str | None,  # The ID of the cell to edit
    "new_source": str,  # The new source for the cell
    "cell_type": "code" | "markdown" | None,  # The type of the cell
    "edit_mode": "replace" | "insert" | "delete" | None,  # Edit operation type
}
```

**Output:**

```python theme={null}
{
    "message": str,  # Success message
    "edit_type": "replaced" | "inserted" | "deleted",  # Type of edit performed
    "cell_id": str | None,  # Cell ID that was affected
    "total_cells": int,  # Total cells in notebook after edit
}
```

### WebFetch

**Tool name:** `WebFetch`

**Input:**

```python theme={null}
{
    "url": str,  # The URL to fetch content from
    "prompt": str,  # The prompt to run on the fetched content
}
```

**Output:**

```python theme={null}
{
    "bytes": int,  # Size of the fetched content in bytes
    "code": int,  # HTTP response code
    "codeText": str,  # HTTP response code text
    "result": str,  # Processed result from applying the prompt to the content
    "durationMs": int,  # Time to fetch and process the content, in milliseconds
    "url": str,  # URL that was fetched
}
```

### WebSearch

**Tool name:** `WebSearch`

**Input:**

```python theme={null}
{
    "query": str,  # The search query to use
    "allowed_domains": list[str] | None,  # Only include results from these domains
    "blocked_domains": list[str] | None,  # Never include results from these domains
}
```

**Output:**

```python theme={null}
{
    "query": str,  # The search query
    "results": list[str | {"tool_use_id": str, "content": list[{"title": str, "url": str}]}],
    "durationSeconds": float,  # Search duration in seconds
}
```

### TodoWrite

**Tool name:** `TodoWrite`

<Note>
  As of Claude Code v2.1.142, `TodoWrite` is disabled by default. Use `TaskCreate`, `TaskGet`, `TaskUpdate`, and `TaskList` instead. See [Migrate to Task tools](./code-agent-sdk/todo-tracking.md#migrate-to-task-tools) to update your monitoring code, or set `CLAUDE_CODE_ENABLE_TASKS=0` to revert to `TodoWrite`.
</Note>

**Input:**

```python theme={null}
{
    "todos": [
        {
            "content": str,  # The task description
            "status": "pending" | "in_progress" | "completed",  # Task status
            "activeForm": str,  # Active form of the description
        }
    ]
}
```

**Output:**

```python theme={null}
{
    "message": str,  # Success message
    "stats": {"total": int, "pending": int, "in_progress": int, "completed": int},
}
```

### TaskCreate

**Tool name:** `TaskCreate`

**Input:**

```python theme={null}
{
    "subject": str,  # Short task title
    "description": str,  # Detailed task body
    "activeForm": str | None,  # Present-tense label shown while in progress
    "metadata": dict | None,  # Arbitrary caller metadata
}
```

**Output:**

```python theme={null}
{
    "task": {"id": str, "subject": str},  # Created task with assigned ID
}
```

### TaskUpdate

**Tool name:** `TaskUpdate`

**Input:**

```python theme={null}
{
    "taskId": str,  # ID of the task to patch
    "status": Literal["pending", "in_progress", "completed", "deleted"] | None,
    "subject": str | None,
    "description": str | None,
    "activeForm": str | None,
    "addBlocks": list[str] | None,  # Task IDs this task now blocks
    "addBlockedBy": list[str] | None,  # Task IDs that now block this task
    "owner": str | None,
    "metadata": dict | None,
}
```

**Output:**

```python theme={null}
{
    "success": bool,
    "taskId": str,
    "updatedFields": list[str],  # Names of fields that changed
    "error": str | None,
    "statusChange": {"from": str, "to": str} | None,
}
```

### TaskGet

**Tool name:** `TaskGet`

**Input:**

```python theme={null}
{
    "taskId": str,  # ID of the task to read
}
```

**Output:**

```python theme={null}
{
    "task": {
        "id": str,
        "subject": str,
        "description": str,
        "status": Literal["pending", "in_progress", "completed"],
        "blocks": list[str],
        "blockedBy": list[str],
    } | None,  # None when the ID is not found
}
```

### TaskList

**Tool name:** `TaskList`

**Input:**

```python theme={null}
{}
```

**Output:**

```python theme={null}
{
    "tasks": [
        {
            "id": str,
            "subject": str,
            "status": Literal["pending", "in_progress", "completed"],
            "owner": str | None,
            "blockedBy": list[str],
        }
    ],
}
```

### BashOutput

**Tool name:** `BashOutput`

**Input:**

```python theme={null}
{
    "bash_id": str,  # The ID of the background shell
    "filter": str | None,  # Optional regex to filter output lines
}
```

**Output:**

```python theme={null}
{
    "output": str,  # New output since last check
    "status": "running" | "completed" | "failed",  # Current shell status
    "exitCode": int | None,  # Exit code when completed
}
```

### KillBash

**Tool name:** `KillBash`

**Input:**

```python theme={null}
{
    "shell_id": str  # The ID of the background shell to kill
}
```

**Output:**

```python theme={null}
{
    "message": str,  # Success message
    "shell_id": str,  # ID of the killed shell
}
```

### ExitPlanMode

**Tool name:** `ExitPlanMode`

**Input:**

```python theme={null}
{
    "plan": str  # The plan to run by the user for approval
}
```

**Output:**

```python theme={null}
{
    "message": str,  # Confirmation message
    "approved": bool | None,  # Whether user approved the plan
}
```

### ListMcpResources

**Tool name:** `ListMcpResources`

**Input:**

```python theme={null}
{
    "server": str | None  # Optional server name to filter resources by
}
```

**Output:**

```python theme={null}
{
    "resources": [
        {
            "uri": str,
            "name": str,
            "description": str | None,
            "mimeType": str | None,
            "server": str,
        }
    ],
    "total": int,
}
```

### ReadMcpResource

**Tool name:** `ReadMcpResource`

**Input:**

```python theme={null}
{
    "server": str,  # The MCP server name
    "uri": str,  # The resource URI to read
}
```

**Output:**

```python theme={null}
{
    "contents": [
        {"uri": str, "mimeType": str | None, "text": str | None, "blob": str | None}
    ],
    "server": str,
}
```

## Advanced Features with ClaudeSDKClient

### Building a Continuous Conversation Interface

```python theme={null}
from claude_agent_sdk import (
    ClaudeSDKClient,
    ClaudeAgentOptions,
    AssistantMessage,
    TextBlock,
)
import asyncio


class ConversationSession:
    """Maintains a single conversation session with Claude."""

    def __init__(self, options: ClaudeAgentOptions | None = None):
        self.client = ClaudeSDKClient(options)
        self.turn_count = 0

    async def start(self):
        await self.client.connect()
        print("Starting conversation session. Claude will remember context.")
        print(
            "Commands: 'exit' to quit, 'interrupt' to stop current task, 'new' for new session"
        )

        while True:
            user_input = input(f"\n[Turn {self.turn_count + 1}] You: ")

            if user_input.lower() == "exit":
                break
            elif user_input.lower() == "interrupt":
                await self.client.interrupt()
                print("Task interrupted!")
                continue
            elif user_input.lower() == "new":
                # Disconnect and reconnect for a fresh session
                await self.client.disconnect()
                await self.client.connect()
                self.turn_count = 0
                print("Started new conversation session (previous context cleared)")
                continue

            # Send message - the session retains all previous messages
            await self.client.query(user_input)
            self.turn_count += 1

            # Process response
            print(f"[Turn {self.turn_count}] Claude: ", end="")
            async for message in self.client.receive_response():
                if isinstance(message, AssistantMessage):
                    for block in message.content:
                        if isinstance(block, TextBlock):
                            print(block.text, end="")
            print()  # New line after response

        await self.client.disconnect()
        print(f"Conversation ended after {self.turn_count} turns.")


async def main():
    options = ClaudeAgentOptions(
        allowed_tools=["Read", "Write", "Bash"], permission_mode="acceptEdits"
    )
    session = ConversationSession(options)
    await session.start()


# Example conversation:
# Turn 1 - You: "Create a file called hello.py"
# Turn 1 - Claude: "I'll create a hello.py file for you..."
# Turn 2 - You: "What's in that file?"
# Turn 2 - Claude: "The hello.py file I just created contains..." (remembers!)
# Turn 3 - You: "Add a main function to it"
# Turn 3 - Claude: "I'll add a main function to hello.py..." (knows which file!)

asyncio.run(main())
```

### Using Hooks for Behavior Modification

```python theme={null}
from claude_agent_sdk import (
    ClaudeSDKClient,
    ClaudeAgentOptions,
    HookMatcher,
    HookContext,
)
import asyncio
from typing import Any


async def pre_tool_logger(
    input_data: dict[str, Any], tool_use_id: str | None, context: HookContext
) -> dict[str, Any]:
    """Log all tool usage before execution."""
    tool_name = input_data.get("tool_name", "unknown")
    print(f"[PRE-TOOL] About to use: {tool_name}")

    # You can modify or block the tool execution here
    if tool_name == "Bash" and "rm -rf" in str(input_data.get("tool_input", {})):
        return {
            "hookSpecificOutput": {
                "hookEventName": "PreToolUse",
                "permissionDecision": "deny",
                "permissionDecisionReason": "Dangerous command blocked",
            }
        }
    return {}


async def post_tool_logger(
    input_data: dict[str, Any], tool_use_id: str | None, context: HookContext
) -> dict[str, Any]:
    """Log results after tool execution."""
    tool_name = input_data.get("tool_name", "unknown")
    print(f"[POST-TOOL] Completed: {tool_name}")
    return {}


async def user_prompt_modifier(
    input_data: dict[str, Any], tool_use_id: str | None, context: HookContext
) -> dict[str, Any]:
    """Add context to user prompts."""
    original_prompt = input_data.get("prompt", "")

    # Add a timestamp as additional context for Claude to see
    from datetime import datetime

    timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")

    return {
        "hookSpecificOutput": {
            "hookEventName": "UserPromptSubmit",
            "additionalContext": f"[Submitted at {timestamp}] Original prompt: {original_prompt}",
        }
    }


async def main():
    options = ClaudeAgentOptions(
        hooks={
            "PreToolUse": [
                HookMatcher(hooks=[pre_tool_logger]),
                HookMatcher(matcher="Bash", hooks=[pre_tool_logger]),
            ],
            "PostToolUse": [HookMatcher(hooks=[post_tool_logger])],
            "UserPromptSubmit": [HookMatcher(hooks=[user_prompt_modifier])],
        },
        allowed_tools=["Read", "Write", "Bash"],
    )

    async with ClaudeSDKClient(options=options) as client:
        await client.query("List files in current directory")

        async for message in client.receive_response():
            # Hooks will automatically log tool usage
            pass


asyncio.run(main())
```

### Real-time Progress Monitoring

```python theme={null}
from claude_agent_sdk import (
    ClaudeSDKClient,
    ClaudeAgentOptions,
    AssistantMessage,
    ToolUseBlock,
    ToolResultBlock,
    TextBlock,
)
import asyncio


async def monitor_progress():
    options = ClaudeAgentOptions(
        allowed_tools=["Write", "Bash"], permission_mode="acceptEdits"
    )

    async with ClaudeSDKClient(options=options) as client:
        await client.query("Create 5 Python files with different sorting algorithms")

        # Monitor progress in real-time
        async for message in client.receive_response():
            if isinstance(message, AssistantMessage):
                for block in message.content:
                    if isinstance(block, ToolUseBlock):
                        if block.name == "Write":
                            file_path = block.input.get("file_path", "")
                            print(f"Creating: {file_path}")
                    elif isinstance(block, ToolResultBlock):
                        print("Completed tool execution")
                    elif isinstance(block, TextBlock):
                        print(f"Claude says: {block.text[:100]}...")

        print("Task completed!")


asyncio.run(monitor_progress())
```

## Example Usage

### Basic file operations (using query)

```python theme={null}
from claude_agent_sdk import query, ClaudeAgentOptions, AssistantMessage, ToolUseBlock
import asyncio


async def create_project():
    options = ClaudeAgentOptions(
        allowed_tools=["Read", "Write", "Bash"],
        permission_mode="acceptEdits",
        cwd="/home/user/project",
    )

    async for message in query(
        prompt="Create a Python project structure with setup.py", options=options
    ):
        if isinstance(message, AssistantMessage):
            for block in message.content:
                if isinstance(block, ToolUseBlock):
                    print(f"Using tool: {block.name}")


asyncio.run(create_project())
```

### Error handling

```python theme={null}
from claude_agent_sdk import query, CLINotFoundError, ProcessError, CLIJSONDecodeError

try:
    async for message in query(prompt="Hello"):
        print(message)
except CLINotFoundError:
    print(
        "Claude Code CLI not found. Try reinstalling: pip install --force-reinstall claude-agent-sdk"
    )
except ProcessError as e:
    print(f"Process failed with exit code: {e.exit_code}")
except CLIJSONDecodeError as e:
    print(f"Failed to parse response: {e}")
```

### Streaming mode with client

```python theme={null}
from claude_agent_sdk import ClaudeSDKClient
import asyncio


async def interactive_session():
    async with ClaudeSDKClient() as client:
        # Send initial message
        await client.query("What's the weather like?")

        # Process responses
        async for msg in client.receive_response():
            print(msg)

        # Send follow-up
        await client.query("Tell me more about that")

        # Process follow-up response
        async for msg in client.receive_response():
            print(msg)


asyncio.run(interactive_session())
```

### Using custom tools with ClaudeSDKClient

```python theme={null}
from claude_agent_sdk import (
    ClaudeSDKClient,
    ClaudeAgentOptions,
    tool,
    create_sdk_mcp_server,
    AssistantMessage,
    TextBlock,
)
import asyncio
from typing import Any


# Define custom tools with @tool decorator
@tool("calculate", "Perform mathematical calculations", {"expression": str})
async def calculate(args: dict[str, Any]) -> dict[str, Any]:
    try:
        result = eval(args["expression"], {"__builtins__": {}})
        return {"content": [{"type": "text", "text": f"Result: {result}"}]}
    except Exception as e:
        return {
            "content": [{"type": "text", "text": f"Error: {str(e)}"}],
            "is_error": True,
        }


@tool("get_time", "Get current time", {})
async def get_time(args: dict[str, Any]) -> dict[str, Any]:
    from datetime import datetime

    current_time = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
    return {"content": [{"type": "text", "text": f"Current time: {current_time}"}]}


async def main():
    # Create SDK MCP server with custom tools
    my_server = create_sdk_mcp_server(
        name="utilities", version="1.0.0", tools=[calculate, get_time]
    )

    # Configure options with the server
    options = ClaudeAgentOptions(
        mcp_servers={"utils": my_server},
        allowed_tools=["mcp__utils__calculate", "mcp__utils__get_time"],
    )

    # Use ClaudeSDKClient for interactive tool usage
    async with ClaudeSDKClient(options=options) as client:
        await client.query("What's 123 * 456?")

        # Process calculation response
        async for message in client.receive_response():
            if isinstance(message, AssistantMessage):
                for block in message.content:
                    if isinstance(block, TextBlock):
                        print(f"Calculation: {block.text}")

        # Follow up with time query
        await client.query("What time is it now?")

        async for message in client.receive_response():
            if isinstance(message, AssistantMessage):
                for block in message.content:
                    if isinstance(block, TextBlock):
                        print(f"Time: {block.text}")


asyncio.run(main())
```

## Sandbox Configuration

### `SandboxSettings`

Configuration for sandbox behavior. Use this to enable command sandboxing and configure network restrictions programmatically.

```python theme={null}
class SandboxSettings(TypedDict, total=False):
    enabled: bool
    autoAllowBashIfSandboxed: bool
    excludedCommands: list[str]
    allowUnsandboxedCommands: bool
    network: SandboxNetworkConfig
    ignoreViolations: SandboxIgnoreViolations
    enableWeakerNestedSandbox: bool
```

| Property                    | Type                                                  | Default | Description                                                                                                                                                                                                                             |
| :-------------------------- | :---------------------------------------------------- | :------ | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `enabled`                   | `bool`                                                | `False` | Enable sandbox mode for command execution                                                                                                                                                                                               |
| `autoAllowBashIfSandboxed`  | `bool`                                                | `True`  | Auto-approve bash commands when sandbox is enabled                                                                                                                                                                                      |
| `excludedCommands`          | `list[str]`                                           | `[]`    | Commands that always bypass sandbox restrictions (e.g., `["docker"]`). These run unsandboxed automatically without model involvement                                                                                                    |
| `allowUnsandboxedCommands`  | `bool`                                                | `True`  | Allow the model to request running commands outside the sandbox. When `True`, the model can set `dangerouslyDisableSandbox` in tool input, which falls back to the [permissions system](#permissions-fallback-for-unsandboxed-commands) |
| `network`                   | [`SandboxNetworkConfig`](#sandboxnetworkconfig)       | `None`  | Network-specific sandbox configuration                                                                                                                                                                                                  |
| `ignoreViolations`          | [`SandboxIgnoreViolations`](#sandboxignoreviolations) | `None`  | Configure which sandbox violations to ignore                                                                                                                                                                                            |
| `enableWeakerNestedSandbox` | `bool`                                                | `False` | Enable a weaker nested sandbox for compatibility                                                                                                                                                                                        |

#### Example usage

```python theme={null}
from claude_agent_sdk import query, ClaudeAgentOptions, SandboxSettings

sandbox_settings: SandboxSettings = {
    "enabled": True,
    "autoAllowBashIfSandboxed": True,
    "network": {"allowLocalBinding": True},
}

async for message in query(
    prompt="Build and test my project",
    options=ClaudeAgentOptions(sandbox=sandbox_settings),
):
    print(message)
```

<Warning>
  **Unix socket security**: The `allowUnixSockets` option can grant access to powerful system services. For example, allowing `/var/run/docker.sock` effectively grants full host system access through the Docker API, bypassing sandbox isolation. Only allow Unix sockets that are strictly necessary and understand the security implications of each.
</Warning>

### `SandboxNetworkConfig`

Network-specific configuration for sandbox mode.

```python theme={null}
class SandboxNetworkConfig(TypedDict, total=False):
    allowedDomains: list[str]
    deniedDomains: list[str]
    allowManagedDomainsOnly: bool
    allowUnixSockets: list[str]
    allowAllUnixSockets: bool
    allowLocalBinding: bool
    allowMachLookup: list[str]
    httpProxyPort: int
    socksProxyPort: int
```

| Property                  | Type        | Default | Description                                                                                                                                            |
| :------------------------ | :---------- | :------ | :----------------------------------------------------------------------------------------------------------------------------------------------------- |
| `allowedDomains`          | `list[str]` | `[]`    | Domain names that sandboxed processes can access                                                                                                       |
| `deniedDomains`           | `list[str]` | `[]`    | Domain names that sandboxed processes cannot access. Takes precedence over `allowedDomains`                                                            |
| `allowManagedDomainsOnly` | `bool`      | `False` | Managed-settings only: when set in managed settings, ignore `allowedDomains` from non-managed settings sources. Has no effect when set via SDK options |
| `allowUnixSockets`        | `list[str]` | `[]`    | Unix socket paths that processes can access (e.g., Docker socket)                                                                                      |
| `allowAllUnixSockets`     | `bool`      | `False` | Allow access to all Unix sockets                                                                                                                       |
| `allowLocalBinding`       | `bool`      | `False` | Allow processes to bind to local ports (e.g., for dev servers)                                                                                         |
| `allowMachLookup`         | `list[str]` | `[]`    | macOS only: XPC/Mach service names to allow. Supports a trailing wildcard                                                                              |
| `httpProxyPort`           | `int`       | `None`  | HTTP proxy port for network requests                                                                                                                   |
| `socksProxyPort`          | `int`       | `None`  | SOCKS proxy port for network requests                                                                                                                  |

<Note>
  The built-in sandbox proxy enforces the network allowlist based on the requested hostname and does not terminate or inspect TLS traffic, so techniques such as [domain fronting](https://en.wikipedia.org/wiki/Domain_fronting) can potentially bypass it. See [Sandboxing security limitations](./code-sandboxing.md#security-limitations) for details and [Secure deployment](./code-agent-sdk/secure-deployment.md#traffic-forwarding) for configuring a TLS-terminating proxy.
</Note>

### `SandboxIgnoreViolations`

Configuration for ignoring specific sandbox violations.

```python theme={null}
class SandboxIgnoreViolations(TypedDict, total=False):
    file: list[str]
    network: list[str]
```

| Property  | Type        | Default | Description                                 |
| :-------- | :---------- | :------ | :------------------------------------------ |
| `file`    | `list[str]` | `[]`    | File path patterns to ignore violations for |
| `network` | `list[str]` | `[]`    | Network patterns to ignore violations for   |

### Permissions Fallback for Unsandboxed Commands

When `allowUnsandboxedCommands` is enabled, the model can request to run commands outside the sandbox by setting `dangerouslyDisableSandbox: True` in the tool input. These requests fall back to the existing permissions system, meaning your `can_use_tool` handler will be invoked, allowing you to implement custom authorization logic.

<Note>
  **`excludedCommands` vs `allowUnsandboxedCommands`:**

  * `excludedCommands`: A static list of commands that always bypass the sandbox automatically (e.g., `["docker"]`). The model has no control over this.
  * `allowUnsandboxedCommands`: Lets the model decide at runtime whether to request unsandboxed execution by setting `dangerouslyDisableSandbox: True` in the tool input.
</Note>

```python theme={null}
from claude_agent_sdk import (
    query,
    ClaudeAgentOptions,
    HookMatcher,
    PermissionResultAllow,
    PermissionResultDeny,
    ToolPermissionContext,
)


async def can_use_tool(
    tool: str, input: dict, context: ToolPermissionContext
) -> PermissionResultAllow | PermissionResultDeny:
    # Check if the model is requesting to bypass the sandbox
    if tool == "Bash" and input.get("dangerouslyDisableSandbox"):
        # The model is requesting to run this command outside the sandbox
        print(f"Unsandboxed command requested: {input.get('command')}")

        if is_command_authorized(input.get("command")):
            return PermissionResultAllow()
        return PermissionResultDeny(
            message="Command not authorized for unsandboxed execution"
        )
    return PermissionResultAllow()


# Required: dummy hook keeps the stream open for can_use_tool
async def dummy_hook(input_data, tool_use_id, context):
    return {"continue_": True}


async def prompt_stream():
    yield {
        "type": "user",
        "message": {"role": "user", "content": "Deploy my application"},
    }


async def main():
    async for message in query(
        prompt=prompt_stream(),
        options=ClaudeAgentOptions(
            sandbox={
                "enabled": True,
                "allowUnsandboxedCommands": True,  # Model can request unsandboxed execution
            },
            permission_mode="default",
            can_use_tool=can_use_tool,
            hooks={"PreToolUse": [HookMatcher(matcher=None, hooks=[dummy_hook])]},
        ),
    ):
        print(message)
```

This pattern enables you to:

* **Audit model requests**: Log when the model requests unsandboxed execution
* **Implement allowlists**: Only permit specific commands to run unsandboxed
* **Add approval workflows**: Require explicit authorization for privileged operations

<Warning>
  Commands running with `dangerouslyDisableSandbox: True` have full system access. Ensure your `can_use_tool` handler validates these requests carefully.

  If `permission_mode` is set to `bypassPermissions` and `allow_unsandboxed_commands` is enabled, the model can autonomously execute commands outside the sandbox without any approval prompts. This combination effectively allows the model to escape sandbox isolation silently.
</Warning>

## See also

* [SDK overview](./code-agent-sdk/overview.md) - General SDK concepts
* [TypeScript SDK reference](./code-agent-sdk/typescript.md) - TypeScript SDK documentation
* [CLI reference](./code-cli-reference.md) - Command-line interface
* [Common workflows](./code-common-workflows.md) - Step-by-step guides