YB-AI: Unreal Engine 5.8 Native MCP Plugin AI Assistant

YB-AI is an AI assistant built upon the Deep Code CLI project, specifically designed for Unreal Engine 5.8's native MCP (Model Context Protocol) plugin, enabling AI agents to directly control the editor's geometry and other resources.

Project Background

Unreal Engine 5.8 introduced a native MCP plugin, providing powerful capabilities for AI assistants to directly operate the editor. This project solves known issues in the tool calling pipeline (server hangs, editor crashes) and provides a stable, efficient AI assistant for interacting with the UE5.8 editor.

Main Improvements

1. HTTP Transport Mode

• Added HttpMcpClient class supporting HTTP connection to UE5.8's built-in MCP server
• Implemented SSE (Server-Sent Events) listener for real-time server push notifications
• SessionId management for connection stability

2. Enhanced MCP Client

• Full JSON-RPC 2.0 protocol support over HTTP POST
• Automatic SSE stream parsing for tool responses
• Session management via Mcp-Session-Id response header

3. UE5.8 Toolset Support

• Auto-discovery of all UE5.8 MCP toolsets at session start
• Support for 20+ domain toolset plugins (Blueprint, Scene, Asset, Material, etc.)
• Unified call_tool dispatcher for all toolset tools
• Smart plugin guidance when required toolsets are not detected

4. Improved Logging

• Logs no longer print to console, keeping the interface clean
• Log files saved to ~/.deepcode/logs/ with timestamps
• Controlled via debugLogEnabled in settings.json (default: false)

Quick Start

Prerequisites

1. Unreal Engine 5.8: Installed and running
2. Enable MCP Plugins: Enable ModelContextProtocol and ToolsetRegistry plugins in the editor
3. Enable Toolset Plugins (for specific features): Enable MVCBlueprintToolset, StaticMeshToolset, etc. via Edit → Plugins
4. Node.js: v22 or higher

Installation

npm install
npm run build

Configuration

Edit ~/.deepcode/settings.json:

{
  "env": {
    "MODEL": "deepseek-v4-pro",
    "BASE_URL": "https://api.deepseek.com",
    "API_KEY": "sk-your-api-key"
  },
  "thinkingEnabled": true,
  "reasoningEffort": "max"
}

UE5 MCP configuration is built-in! The system automatically adds the default UE5 config (http://localhost:8000/mcp) when no MCP servers are configured.

Run

1. Ensure UE5.8 editor is running with MCP plugin active
2. Run:

   npm start

3. Load the skill: /ue5-mcp
4. The AI will auto-discover all available toolsets and report them

Features

UE5 MCP Skill

• Auto-loaded on startup: Automatically discovers all registered toolsets
• Runtime discovery: Calls list_toolsets + describe_toolset for each session
• Concise logging: Each MCP call outputs [MCP] tool → result
• Smart error handling: Skips non-existent methods, retries on timeout

Toolset Plugins (Enable via Edit → Plugins)

Plugin	Function
MVCBlueprintToolset	Blueprint tools (53 operations)
StaticMeshToolset	Static mesh tools
EditorScriptingToolset	Editor scripting
SceneTools	Scene/Actor manipulation
MaterialTools	Material creation/editing
PCGToolset	Procedural content generation
AnimationAssistantToolset	Animation tools
... and 15+ more	Diverse UE editor toolsets

Slash Commands

Command	Action
/ue5-mcp	Load UE5 MCP skill
/skills	List available skills
/mcp	View MCP server status
/new	Start new conversation
/model	Switch model/thinking mode

Deployment Options

Portable Mode (Recommended for UE Integration)

Copy these to any folder:

• dist/ - Built CLI
• templates/ - Templates
• nodejs/ - Portable Node.js runtime
• YB-AI-Manager.exe - UI manager (optional)

UI Manager

A lightweight C# WinForms UI manager for multiple UE project management. See ui/ directory.

Documentation

• UE5.8 MCP Toolset Plugin Guide (Chinese) - Details on enabling all toolset plugins
• Portable Deployment Guide (Chinese)
• UI Manager Build Guide (Chinese)

License

MIT

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Let AI become your Unreal Engine development partner!