Unity MCP Server

What is Unity MCP Server?

A lightweight Model Context Protocol (MCP) server designed to work with Unity applications. It provides a standardized way for Unity applications to interact with Large Language Models (LLMs) via stdio-based transport, built on the official MCP C# SDK.

How to use Unity MCP Server?

Clone the repository, build with dotnet build, and run with dotnet run. From Unity, launch the server as a subprocess and communicate over standard input/output. Use the included sample tools like Echo, GetServerInfo, ListTools, ProcessJsonData, and SimulateGameObjectOperation.

Key features of Unity MCP Server

• Cross-platform compatibility (Windows, macOS, Linux)
• Simple stdio-based transport for easy integration
• Sample Unity-specific tool implementations
• Built on the official MCP C# SDK
• Enhanced logging for debugging

Use cases of Unity MCP Server

• Testing Unity-LLM integration with a lightweight local server
• Prototyping tool calls from a Unity client to an LLM
• Building custom Unity editor tools that leverage model capabilities
• Demonstrating MCP concepts in a Unity development workflow

FAQ from Unity MCP Server

What prerequisites are needed?

.NET 9.0 SDK or later for the server, and Unity 2022.3.19f1 or later for Unity client integration.

What transport protocol does the server use?

It uses a simple stdio-based transport; the server communicates via standard input/output streams.

How can I add custom tools?

Create a new class with the [McpServerToolType] attribute and add methods with the [McpServerTool] attribute, then rebuild the server.

What sample tools are included?

Echo (echoes a message), GetServerInfo (returns server information), ListTools (lists all tools), ProcessJsonData (processes JSON data), and SimulateGameObjectOperation (simulates move, rotate, scale, destroy).

How do I run the server from Unity?

Launch the server as a subprocess with dotnet pointing to the built DLL, then send JSON tool requests via standard input and read responses from standard output.