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 packaged server folder (Server) if you want to run the bundled implementation.
   • Install Python and/or uv/uvx if missing so the server can be managed locally.
   • 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, OpenClaw, 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.
  • Rebuild MCP Server: Rebuilds the Python based MCP server
  • Select server folder…: Choose the local Server folder (dev only; usually not needed when using uvx).
  • Verify again: Re-checks server presence.
  • If Python isn’t detected, use “Open Install Instructions”.
• HTTP Server Command foldout:
  • Expands to display the exact uvx command Unity will run.
  • Includes a copy button and the “Start Local HTTP Server” action so you can launch or reuse the command elsewhere.

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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 uvx with the current package version:
      • Command: uvx (or your overridden path)
      • Args: --from <git-url> mcp-for-unity
    • Manual Setup: Opens a window with a pre-filled JSON snippet to copy/paste into your client config.
    • Choose UV Install Location: If uv/uvx isn’t on PATH, select the executable.
    • 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.
  • OpenClaw:
    • Uses ~/.openclaw/openclaw.json and the openclaw-mcp-bridge plugin.
    • MCP for Unity writes plugins.entries.openclaw-mcp-bridge.config.servers.unityMCP.
    • OpenClaw follows the currently selected MCP for Unity transport (HTTP or stdio).
    • The bridge exposes a proxy tool such as unityMCP__call.

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

• Use Cmd+Shift+M (macOS) / Ctrl+Shift+M (Windows, Linux) to toggle the MCP for Unity window.
• Enable “Show Debug Logs” in the header for more details in the Console when diagnosing issues.

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