Funplay MCP for Unity

The Most Advanced MCP Server for Unity Editor

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💖 If you find this project useful, please consider giving it a Star. It helps more Unity developers discover it and supports ongoing development.

Funplay MCP for Unity is an MIT-licensed Unity Editor MCP server that lets AI assistants like Claude Code, Cursor, Windsurf, Codex, and VS Code Copilot operate directly inside your running Unity project.

Describe your game in one sentence — your AI assistant builds it in Unity through Funplay MCP for Unity's 79 built-in tools for scene creation, script generation, runtime validation, input simulation, performance analysis, and editor automation.

"Build a snake game with a 10x10 grid, food spawning, score UI, and game-over screen"

Your AI assistant handles it through Funplay MCP for Unity: creates the scene, generates all scripts, sets up the UI, and configures the game logic — all from a single prompt.

Quick Start

If you just want to get connected fast, do these three things:

• Install the Unity package from the Git URL
• Start Funplay > MCP Server
• Use the built-in one-click client configuration

1. Install via UPM (Git URL)

In Unity, go to Window → Package Manager → + → Add package from git URL:

https://github.com/FunplayAI/funplay-unity-mcp.git

💡 Before you clone or install, a quick ⭐ on GitHub would be greatly appreciated.

2. Start the MCP Server

Menu: Funplay → MCP Server to start the server.

The server starts on http://127.0.0.1:8765/ by default.

3. Configure Your AI Client

Use the built-in One-Click MCP Configuration in the Funplay > MCP Server window first.

Select your target client, click Configure, and the package writes the recommended MCP config entry for you.

If you want project-specific AI guidance for the current Unity project, open Funplay → Project Skills (Experimental) to choose supported platforms and install built-in plus optional skills.

If you prefer to edit config files manually, use the examples below as fallback references:

{
  "mcpServers": {
    "funplay": {
      "type": "http",
      "url": "http://127.0.0.1:8765/"
    }
  }
}

{
  "mcpServers": {
    "funplay": {
      "url": "http://127.0.0.1:8765/"
    }
  }
}

{
  "servers": {
    "funplay": {
      "type": "http",
      "url": "http://127.0.0.1:8765/"
    }
  }
}

{
  "mcpServers": {
    "funplay": {
      "url": "http://127.0.0.1:8765/"
    }
  }
}

{
  "mcpServers": {
    "funplay": {
      "type": "http",
      "url": "http://127.0.0.1:8765/"
    }
  }
}

[mcp_servers.funplay]
url = "http://127.0.0.1:8765/"

4. Verify the Connection

Open your AI client and try a few safe requests first:

• "Call get_scene_info and tell me what scene is open."
• "Read unity://project/context and summarize the current editor state."
• "Use execute_code to return the active scene name."

If those work, the MCP server, resources, and primary execution tool are connected correctly.

5. Start Building

Open your AI client and try: "Create a 3D platformer level with 5 floating platforms"

Before You Start

• This package is Editor-only. It does not add runtime components to your built game.
• The MCP server starts on http://127.0.0.1:8765/ by default.
• Local MCP server settings are stored in UserSettings/FunplayMcpSettings.json.
• The package defaults to the core MCP tool profile to reduce tool-list noise for AI clients. core currently exposes 19 high-signal tools centered on execute_code, play mode control, input simulation, screenshots, performance inspection, logs, and compilation checks. Switch to full in the MCP Server window if you want all 79 tools exposed.
• All exposed MCP tools run directly. There is no extra approval toggle.
• Menu: Funplay > Check for Updates can refresh Git installs in place or download and import the latest unitypackage automatically.

Why This Project

• execute_code First — The package is optimized around one high-flexibility C# execution tool for rich editor/runtime orchestration when many small tools would be noisy
• Play Mode Automation — Enter play mode, simulate keyboard/mouse input, capture screenshots, inspect logs, and validate behavior from the same MCP session
• Project Context Built In — Exposes live resources for project state, active scene, selection, compilation, console output, and MCP interaction history
• Focused by Default, Full When Needed — core exposes a compact high-signal toolset; full exposes all 79 tools
• Single Unity Package — No extra approval UI, no external daemon to click through, and no Python requirement for the Unity-side plugin itself
• Extensible — Add custom tools with attribute-based discovery, or connect Unity to external MCP services when needed

Highlights

• 79 Built-in Tools — Scene editing, assets, scripts, play mode control, screenshots, performance analysis, prompts, resources, and editor automation across 19 modules
• Resources & Prompts — Live project context, scene/selection/error resources, resource templates, and reusable workflow prompts
• Input Simulation + Screenshots — Drive play mode with keyboard/mouse simulation and verify results with game/scene captures
• Built-in Updating — Check for updates from the Unity menu and either re-pull the Git package or auto-import the latest unitypackage
• One-Click Client Configuration — Generate MCP config entries for Claude Code, Cursor, VS Code, Kiro, Trae, Codex, and similar clients directly from the Unity window
• Project Skills Manager (Experimental) — Configure project-level skills for supported AI clients, with built-in skills plus optional installable skills
• Vendor Agnostic — Works with any AI client that supports MCP: Claude Code, Cursor, Windsurf, Codex, VS Code Copilot, etc.

Comparison With Coplay

The table below compares this repository with the publicly documented behavior of Coplay's open-source unity-mcp repository on GitHub.

Source for Coplay column: CoplayDev/unity-mcp

MCP Capabilities

The current open-source package exposes four high-value capability layers:

• Tools — 79 total tools in full, 19 focused tools in core
• Primary execution — execute_code for rich editor/runtime orchestration
• Prompts — workflow prompts like fix_compile_errors, runtime_validation, and create_playable_prototype
• Resources — project context, scene summaries, selection state, compile errors, console errors, MCP interaction history, plus resource templates for scene objects, components, and asset paths

Built-in Tools

Funplay MCP for Unity currently ships with 79 tool functions across 19 modules:

Adding Custom Tools

Create your own tools with simple attribute annotations:

using System.ComponentModel;

[ToolProvider("MyTools")]
public static class MyCustomTools
{
    [Description("Spawns enemies at random positions in the scene")]
    public static string SpawnEnemies(
        [ToolParam("Number of enemies to spawn", Required = true)] int count,
        [ToolParam("Prefab path in Assets")] string prefabPath)
    {
        // Your implementation here
        return $"Spawned {count} enemies";
    }
}

Methods are automatically discovered, converted to snake_case (spawn_enemies), and exposed via MCP with JSON Schema definitions.

Architecture

MCP Server (HTTP JSON-RPC 2.0)
    └─ MCPRequestHandler (protocol handling)
        └─ MCPExecutionBridge
            └─ FunctionInvokerController (reflection-based invocation)
                └─ Tool Functions (79 built-in tools across 19 modules)

External AI Client → HTTP Request → MCPRequestHandler → MCPExecutionBridge → FunctionInvokerController → tool method

Requirements

• Unity 2022.3 or later
• .NET / Mono with Newtonsoft.Json

Contributing

Contributions are welcome! Please read the Contributing Guide before submitting a PR.

License

MIT — Free to use, modify, distribute, and integrate into commercial or open-source projects.