Yamu

Yamu (Yet Another Minimal MCP server for Unity) is an experimental MCP (Model Context Protocol) server that enables AI coding agents to interact with Unity projects.

Features

• compile_and_wait - Triggers Unity Editor compilation, waits for completion, and returns compilation results including any errors
• run_tests - Executes Unity Test Runner tests (both EditMode and PlayMode) with real-time status monitoring and detailed result reporting

Purpose

This proof-of-concept demonstrates how AI coding agents (Claude Code, Gemini CLI, etc.) can autonomously iterate through edit-compile-debug cycles in Unity development when provided with these basic compilation feedback mechanisms via MCP.

Prerequisites

• Platform: macOS (only tested platform)
• Node.js: Required to run the intermediate server

  brew install node
  

Installation

1. Install the Package

You can install the Yamu package (jp.keijiro.yamu) via the “Keijiro” scoped registry using the Unity Package Manager. To add the registry to your project, follow these instructions.

2. Add the MCP Server to the AI Agent

You can either follow the steps in yamu-mcp-setup.md manually, or let the AI agent do it for you. For example, if you’re using Gemini CLI:

You're Gemini CLI. Follow yamu-mcp-setup.md

The “You’re —” statement is important, as some AI agents don’t know what they are unless explicitly told.

Note: You’ll need to update this configuration each time you upgrade Yamu. You can simply run the same prompt again to refresh it.