Unity Code MCP

Description

Unity Code MCP is a coding focused Model Context Protocol (MCP) server that enables AI agents to write Unity code autonomously.

🎯 Why Unity Code MCP?

Unity Code MCP is a high-performance, coding-focused MCP server built in Rust. It handles Unity's compilation cycles gracefully while providing only the essential tools needed for autonomous code development: compilation feedback and test execution.

This MCP server enables AI agents to develop Unity code autonomously with exceptional speed and reliability - write code, compile, fix compile errors, test, fix bugs, repeat, just like how a human would.

✨ Key Features

• 🤖 Coding-Optimized: Streamlined tools designed for efficient AI agent coding workflows
• ⚡ High Performance: Built in Rust for exceptional speed, minimal memory usage, and lightning-fast response times
• 🎯 Efficient Communication: Minimal token usage with essential operations, only returns relevant information
• 🧪 Test-Driven: Comprehensive test execution and reporting capabilities
• 📦 Self-Contained: Single binary with no runtime dependencies (no Node.js, Python, or .NET required)

🛠️ MCP Server Tools

Unity Code MCP provides 2 tools for autonomous code development:

1. Asset Database Refresh

• Triggers Unity compilation and asset processing
• Returns compile errors and other non compile warning and errors only include the logs during the refresh
• Handles domain reload gracefully

Asset database refresh tool in action:

2. Test Execution

• Runs Unity tests with comprehensive reporting
• Provides detailed stack traces and logs for failures
• Supports both EditMode and PlayMode tests

Test execution tool in action:

🚀 Autonomous AI agent workflow example

Once configured, AI agents can develop Unity code completely autonomously:

User: "Create a player controller that moves with WASD keys and has jump functionality. Make sure it's fully tested."

AI: I'll create a complete player controller with movement and jumping, then write comprehensive tests.

1. [AI writes PlayerController.cs with movement logic]
2. [AI calls: refresh_asset_database]
   → Result: "Compilation failed: CS0246: The type or namespace name 'Rigidbody' could not be found"
3. [AI fixes the missing using UnityEngine; statement]
4. [AI calls: refresh_asset_database]
   → Result: "Compilation successful, no errors"
5. [AI writes PlayerControllerTests.cs with movement and jump tests]
6. [AI calls: run_tests]
   → Result: "5 tests passed, 2 tests failed: NullReferenceException in Jump_ShouldApplyUpwardForce, ArgumentException in Move_WithInvalidInput"
7. [AI analyzes failures and fixes null reference and input validation bugs]
8. [AI calls: refresh_asset_database]
   → Result: "Compilation successful, no errors"
9. [AI calls: run_tests]
   → Result: "All 7 tests passed successfully"

AI: ✅ Complete! Created a fully functional PlayerController with WASD movement, jump mechanics, and comprehensive test coverage. All tests are passing.

This demonstrates true autonomous development - from user request to fully tested, working Unity code without any human intervention.

AI agent in action, tell Kimi K2 to fix compile errors in Unity project with no context:

📦 Installation

Prerequisites

• Unity 6.0 or higher
• Rust toolchain (for building from source)
• CMake and a C compiler (required for building dependencies)

Step 1: Install Unity Package

Install the Visual Studio Code Editor package in your Unity project.

Step 2: Get the Binary

Option A: Download Release (Recommended) (Windows Only)

• Download the latest binary from the Releases page

Option B: Build from Source

cargo build --release

Step 3: Configure Your AI Assistant

Add the MCP server to your AI assistant configuration:

For Claude Desktop/Cursor/Trae:

{
  "mcpServers": {
    "unity-code": {
      "command": "/path/to/unity-code-mcp",
      "env": {
        "UNITY_PROJECT_PATH": "/path/to/your/unity/project"
      }
    }
  }
}

For VS Code with MCP Extension:

{
  "mcp.servers": {
    "unity-code": {
      "command": "/path/to/unity-code-mcp",
      "args": [],
      "env": {
        "UNITY_PROJECT_PATH": "/path/to/your/unity/project"
      }
    }
  }
}

Important: Use absolute paths for both the binary and Unity project directory.

Platform support

The code is cross platform, but I can't build or test for other platforms, because I only use Windows. If there are platform specific bugs, you have to fix them yourself.

🧪 Development & Testing

Running Tests

To run the test suite:

1. Start Unity Editor with the embedded test project:

   # Open Unity Editor and load the project at:
   # ./UnityProject

2. Run tests (single-threaded to avoid Unity conflicts):

   cargo test -- --test-threads=1

Note: Tests require a running Unity Editor instance with the embedded project loaded. Tests may take 30-60 seconds to complete due to Unity Editor interactions.

Building from Source

Prerequisites

• C Compiler: Required for building aws-lc-rs dependency
  • Windows: MSVC (Visual Studio Build Tools)
  • macOS: Xcode Command Line Tools (xcode-select --install)
  • Linux: GCC (sudo apt-get install build-essential on Ubuntu/Debian)
• CMake: Required for building the aws-lc-rs dependency
  • Windows: Follow the official guide
  • macOS: brew install cmake
  • Linux: sudo apt-get install cmake (Ubuntu/Debian)

Build Commands

# Debug build
cargo build

# Release build (recommended for production)
cargo build --release

🤝 Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Run tests with cargo test -- --test-threads=1
4. Submit a pull request

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🔗 Related Projects

• Visual Studio Code Editor for Unity - Required Unity package
• Model Context Protocol - The protocol specification
• Unity Code Pro VS Code Extension - VS Code extension that is related