unity-mcp/UnityMcpBridge

MCP for Unity — Editor Plugin Guide

Use this guide to configure and run MCP for Unity inside the Unity Editor. Installation is covered elsewhere; this document focuses on the Editor window, client configuration, and troubleshooting.

Open the window

• Unity menu: Window > MCP for Unity

The window has four areas: Server Status, Unity Bridge, MCP Client Configuration, and Script Validation.

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Quick start

1. Open Window > MCP for Unity.
2. Click “Auto-Setup”.
3. If prompted:
   • Select the server folder that contains server.py (UnityMcpServer~/src).
   • Install Python and/or uv if missing.
   • For Claude Code, ensure the claude CLI is installed.
4. Click “Start Bridge” if the Unity Bridge shows “Stopped”.
5. Use your MCP client (Cursor, VS Code, Windsurf, Claude Code) to connect.

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Server Status

• Status dot and label:
  • Installed / Installed (Embedded) / Not Installed.
• Mode and ports:
  • Mode: Auto or Standard.
  • Ports: Unity (varies; shown in UI), MCP 6500.
• Actions:
  • Auto-Setup: Registers/updates your selected MCP client(s), ensures bridge connectivity. Shows “Connected ✓” after success.
  • Repair Python Env: Rebuilds a clean Python environment (deletes .venv, runs uv sync).
  • Select server folder…: Choose the folder containing server.py.
  • Verify again: Re-checks server presence.
  • If Python isn’t detected, use “Open Install Instructions”.

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Unity Bridge

• Shows Running or Stopped with a status dot.
• Start/Stop Bridge button toggles the Unity bridge process used by MCP clients to talk to Unity.
• Tip: After Auto-Setup, the bridge may auto-start in Auto mode.

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MCP Client Configuration

• Select Client: Choose your target MCP client (e.g., Cursor, VS Code, Windsurf, Claude Code).
• Per-client actions:
  • Cursor / VS Code / Windsurf:
    • Auto Configure: Writes/updates your config to launch the server via uv:
      • Command: uv
      • Args: run --directory server.py
    • Manual Setup: Opens a window with a pre-filled JSON snippet to copy/paste into your client config.
    • Choose uv Install Location: If uv isn’t on PATH, select the uv binary.
    • A compact “Config:” line shows the resolved config file name once uv/server are detected.
  • Claude Code:
    • Register with Claude Code / Unregister MCP for Unity with Claude Code.
    • If the CLI isn’t found, click “Choose Claude Install Location”.
    • The window displays the resolved Claude CLI path when detected.

Notes:

• The UI shows a status dot and a short status text (e.g., “Configured”, “uv Not Found”, “Claude Not Found”).
• Use “Auto Configure” for one-click setup; use “Manual Setup” when you prefer to review/copy config.

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Script Validation

• Validation Level options:
  • Basic — Only syntax checks
  • Standard — Syntax + Unity practices
  • Comprehensive — All checks + semantic analysis
  • Strict — Full semantic validation (requires Roslyn)
• Pick a level based on your project’s needs. A description is shown under the dropdown.

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Troubleshooting

• Python or uv not found:
  • Help: Fix MCP for Unity with Cursor, VS Code & Windsurf
• Claude CLI not found:
  • Help: Fix MCP for Unity with Claude Code

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Tips

• Enable “Show Debug Logs” in the header for more details in the Console when diagnosing issues.

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