Explicit uppercase for tool calls breaks with local LLMs, that expect lowercase values

[chasseuragace]

Environment

• SDK version: 0.1.9
• Python version: 3.10.20
• OS / platform: macOS ARM64 (darwin)
• Install method: pip install google-antigravity

Description

FunctionDeclaration.from_callable_with_api_option(...) emits JSON Schema with uppercase enum values for type fields ("OBJECT", "STRING", etc.). OpenAI-compatible endpoints require lowercase ("object", "string"). This breaks all custom Python tools when using LocalOpenAIAgentConfig with an OpenAI-compatible local server (Ollama, LM Studio, etc.).

Steps to Reproduce

1. Install google-antigravity via pip.
2. Run a local OpenAI-compatible server, e.g. LM Studio at http://127.0.0.1:1234.
3. Create a simple custom tool:

   def get_temperature(location: str) -> str:
       return f"The temperature in {location} is 72°F."

4. Configure the agent:

   config = LocalOpenAIAgentConfig(
       model="google/gemma-4-e2b",
       base_url="http://127.0.0.1:1234",
       tools=[get_temperature],
   )

5. Send a prompt that triggers the tool: "What's the temperature in Mountain View?"

Expected Behavior

The agent calls get_temperature with {"location": "Mountain View"} and returns the result.

Actual Behavior

The local LLM server returns HTTP 400:

{
  "error": [
    {
      "code": "invalid_union_discriminator",
      "options": ["object"],
      "path": [2, "function", "parameters", "type"],
      "message": "Invalid discriminator value. Expected 'object'"
    }
  ]
}

The SDK then surfaces: model output error: model output must contain either output text or tool calls, these cannot both be empty, please try again

Additional Context

• The broken schema originates in google/antigravity/connections/local/local_connection.py:199-213 (callable_to_tool_proto).
• decl.parameters.model_dump(exclude_none=True) preserves genai_types.Type enum values as uppercase strings.
• Workaround: wrap tools in ToolWithSchema with an explicit lowercase JSON Schema.
• Local patch applied in source tree: recursive _normalize_schema_types() converts genai_types.Type values to lowercase before json.dumps().

[RounakKumarAgarwal]

Hi I would like to work on this bug , can you assign it to me @chasseuragace

[NTaylorMullen]

Hi @RounakKumarAgarwal unfortunately we don't take PRs to this repo but super appreciate the energy!

[RounakKumarAgarwal]

Please let me know how can I contribute engage here? @NTaylorMullen.