uMCP (Unity Editor) MCP server

This server implements the Model Context Protocol (MCP) specifically for Unity, enabling AI agents to interact with Unity applications through a streamlined, secure interface. It provides a lightweight solution that communicates directly with MCP clients using Streamable HTTP without requiring additional dependencies.

Installation

Prerequisites

• Unity Editor: Version 2022.3 LTS or newer
• An MCP client that supports Streamable HTTP (such as VSCode Agent Mode, Cursor, or CLINE)

Installing the Core Framework

Option 1: Using OpenUPM

openupm add com.natsuneko.modelcontextprotocol.core-framework

Option 2: Using Git URL in Unity

1. Open your Unity project
2. Go to Window > Package Manager
3. Click the + button and select Add package from git URL...
4. Enter the following URL:

   https://github.com/mika-f/uMCP.git?path=/Assets/NatsunekoLaboratory/ModelContextProtocol/CoreFramework
   

5. Click Add

Installing Additional Tools

Management Tools

Using OpenUPM:

openupm add com.natsuneko.modelcontextprotocol.management-tools

Using Git URL:

1. Go to Window > Package Manager
2. Click the + button and select Add package from git URL...
3. Enter:

   https://github.com/mika-f/uMCP.git?path=/Assets/NatsunekoLaboratory/ModelContextProtocol/MagagementTools
   

VRChat World Tools

Using OpenUPM:

openupm add com.natsuneko.modelcontextprotocol.vrchat-world-tools

Configuring Your MCP Client

Connect your MCP client to the server using one of these endpoints:

http://localhost:7225/sse

or

http://localhost:7225/mcp

Example Configuration for VSCode Agent Mode

Add this to your configuration:

{
  "servers": {
    "uMCP": {
      "url": "http://localhost:7225/mcp"
    }
  }
}

Using the MCP Server

1. Open your Unity project
2. The MCP server automatically starts when you run the Unity project
3. Launch your MCP client (VSCode Agent Mode, Cursor, CLINE, etc.)
4. Your AI agent can now interact with your Unity application through the MCP protocol

Creating Custom Commands

You can extend the functionality by creating your own custom commands:

using System;
using System.ComponentModel;

using NatsunekoLaboratory.ModelContextProtocol.CoreFramework.Attributes;
using NatsunekoLaboratory.ModelContextProtocol.CoreFramework.Models;
using NatsunekoLaboratory.ModelContextProtocol.CoreFramework.Protocol.Abstractions;
using NatsunekoLaboratory.ModelContextProtocol.CoreFramework.Protocol.Interfaces;

namespace NatsunekoLaboratory.Examples.MyCustomCommands
{
    [McpServerToolType]
    public class MyCustomCommand
    {
        [McpServerTool]
        [Description("This is a custom command that does something.")]
        public static IToolResult Execute([Description("An example parameter for the custom command.")] string exampleParameter)
        {
            // Your custom command logic here
            return new TextResult($"Executed custom command with parameter: {exampleParameter}");
        }
    }
}

Key Features

• Security: The server prevents AI from executing arbitrary code, limiting operations to pre-authorized commands only
• Extensibility: Easily add custom commands using the McpServerToolType and McpServerTool attributes
• Efficiency: Direct communication with MCP clients using Streamable HTTP without additional runtime dependencies

How to install this MCP server

For Claude Code

To add this MCP server to Claude Code, run this command in your terminal:

claude mcp add-json "uMCP" '{"url":"http://localhost:7225/sse"}'

See the official Claude Code MCP documentation for more details.

For Cursor

There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.

If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.

Adding an MCP server to Cursor globally

To add a global MCP server go to Cursor Settings > Tools & Integrations and click "New MCP Server".

When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:

{
    "mcpServers": {
        "uMCP": {
            "url": "http://localhost:7225/sse"
        }
    }
}

Adding an MCP server to a project

To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.

How to use the MCP server

Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.

The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.

You can also explicitly ask the agent to use the tool by mentioning the tool name and describing what the function does.

For Claude Desktop

To add this MCP server to Claude Desktop:

1. Find your configuration file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

2. Add this to your configuration file:

{
    "mcpServers": {
        "uMCP": {
            "url": "http://localhost:7225/sse"
        }
    }
}

3. Restart Claude Desktop for the changes to take effect