unity-mcp

<p align="center">
  <h1 align="center">KitWright MCP for Unity</h1>
  <p align="center">
    <strong>The Most Advanced MCP Server for Unity Editor</strong>
  </p>
  <p align="center">
    <a href="#"><img src="https://img.shields.io/badge/Unity-2022.3%2B-black?logo=unity" alt="Unity 2022.3+"></a>
    <a href="#"><img src="https://img.shields.io/badge/License-MIT-blue.svg" alt="License: MIT"></a>
    <a href="#"><img src="https://img.shields.io/badge/MCP-Compatible-green" alt="MCP Compatible"></a>
    <a href="#"><img src="https://img.shields.io/badge/Platform-Editor%20Only-orange" alt="Editor Only"></a>
  </p>
  <p align="center">
    <a href="./README_CN.md">中文</a> | English
  </p>
  <p align="center">
    <img src="./Documentation~/Video_Logo.gif" alt="The Most Advanced MCP Server for Unity" width="60%">
  </p>
</p>

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

---

KitWright MCP for Unity is an MIT-licensed Unity Editor MCP server that lets AI assistants like Claude Code, Cursor, LM Studio, 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 KitWright MCP for Unity's 274 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 KitWright MCP for Unity: creates the scene, generates all scripts, sets up the UI, and configures the game logic — all from a single prompt.

<p align="center">
  <img src="./Documentation~/demo.gif" alt="KitWright MCP for Unity — demo" width="100%">
</p>
<p align="center"><em>Demo — AI searches project prefabs and builds a city scene through MCP tools. <a href="https://github.com/kitwright/unity-mcp/raw/main/Documentation~/demo.mp4">Watch HD MP4</a>.</em></p>

## Quick Start

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

- Install the Unity package from the Git URL
- Open `Window > KitWright > MCP Window` and start the server from the **Server** tab
- 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/kitwright/unity-mcp.git
```

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

### Optional: Install via OpenUPM

If you want Unity Package Manager to show registry-backed package version history and allow version selection, install from OpenUPM instead of Git.

Using the OpenUPM CLI:

```bash
openupm add com.kitwright.unity.mcp
```

Or add the scoped registry manually in `Packages/manifest.json`:

```json
{
  "scopedRegistries": [
    {
      "name": "OpenUPM",
      "url": "https://package.openupm.com",
      "scopes": [
        "com.kitwright"
      ]
    }
  ],
  "dependencies": {
    "com.kitwright.unity.mcp": "1.0.0"
  }
}
```

If you installed from a Git URL before, remove the Git dependency first, then install from OpenUPM. Git-installed packages only show the resolved Git version in Unity and do not get the registry-backed Version History list.

### Optional: Install from the Unity Asset Store

Importing the Asset Store package shows a **This Unity Package has Package Manager dependencies** dialog. Choose **Install/Upgrade** — the package needs `com.unity.nuget.newtonsoft-json`, and skipping the prompt leaves the project without it, which stops every KitWright script from compiling.

If you already chose Skip, the package offers to install the dependency for you on the next domain reload; you can also add it yourself from **Window → Package Manager → + → Add package by name**:

```
com.unity.nuget.newtonsoft-json
```

### 2. Start the MCP Server

**Menu: Window → KitWright → MCP Window**, then start the server from the **Server** tab.

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

**Broker Mode** is the default transport. It runs a tiny local broker with Unity's bundled Mono, keeps the same `127.0.0.1` port for MCP clients, requires no client config change, and holds the connection across Unity script recompiles and Play Mode domain reloads. If the broker cannot start, the server falls back to direct in-process HTTP automatically; you can also turn broker mode off in the **Server** tab to use direct HTTP always.

The window has five tabs: **Server**, **Settings**, **Skills**, **Tool Exposure**, and **Integrations**.

Open the **Tool Exposure** tab if you want to edit the exact tools exposed by `core` or `full`.

Open the **Settings** tab if you need to adjust `execute_code` safety defaults or plugin debug logging.

### 3. Configure Your AI Client

Use the built-in **One-Click MCP Configuration** in the **Server** tab first.

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

For Claude Code, Cursor, and Codex, click **Configure + Skills** to also install the default project MCP workflow skill.

If you want project-specific AI guidance for the current Unity project, open the **Skills** tab to choose supported platforms and install the default `unity-mcp-workflow` skill.

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

<details>
<summary>Claude Code / Claude Desktop</summary>

```json
{
  "mcpServers": {
    "kitwright": {
      "type": "http",
      "url": "http://127.0.0.1:8765/"
    }
  }
}
```

</details>

<details>
<summary>Cursor</summary>

```json
{
  "mcpServers": {
    "kitwright": {
      "url": "http://127.0.0.1:8765/"
    }
  }
}
```

</details>

<details>
<summary>LM Studio</summary>

LM Studio is not one of the one-click targets — its `mcp.json` location varies by version and platform. Open **Program > Install > Edit mcp.json** in LM Studio and paste the entry below.

```json
{
  "mcpServers": {
    "kitwright": {
      "url": "http://127.0.0.1:8765/"
    }
  }
}
```

</details>

<details>
<summary>VS Code</summary>

```json
{
  "servers": {
    "kitwright": {
      "type": "http",
      "url": "http://127.0.0.1:8765/"
    }
  }
}
```

</details>

<details>
<summary>Trae</summary>

```json
{
  "mcpServers": {
    "kitwright": {
      "url": "http://127.0.0.1:8765/"
    }
  }
}
```

</details>

<details>
<summary>Kiro</summary>

```json
{
  "mcpServers": {
    "kitwright": {
      "type": "http",
      "url": "http://127.0.0.1:8765/"
    }
  }
}
```

</details>

<details>
<summary>Codex</summary>

```toml
[mcp_servers.kitwright]
url = "http://127.0.0.1:8765/"
```

</details>

<details>
<summary>Windsurf</summary>

Use the same JSON structure as Cursor unless your local Windsurf version requires a different MCP config format.

</details>

### 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/KitWrightMcpSettings.json`.
- The package defaults to the `core` MCP tool profile to reduce tool-list noise for AI clients. `core` currently exposes 43 high-signal tools centered on `execute_code`, play mode control, input simulation, screenshots, performance inspection, logs, compilation checks, structured object location and component editing, editor selection / prefab-stage state, live C# API reflection, Unity documentation lookup, and `execute_menu_item` as a low-friction fallback. Switch to `full` in the **Server** tab if you want all 274 tools exposed.
- `execute_code` safety checks and the stricter filesystem guard are enabled by default from the **Settings** tab. The guard blocks obvious destructive snippets, broad `System.IO` writes, raw file streams, and absolute/user/system/traversal paths. It catches accidents, not intent: `safety_checks` is a tool argument, so any client that can call `execute_code` can pass `safety_checks=false` and skip both the source blocklist and the compiled-assembly guard. It is neither a sandbox nor a security boundary — see [SECURITY.md](./SECURITY.md).
- Plugin debug logging is off by default and can also be enabled from the **Settings** tab. Warnings and errors are always written to the Unity Console.
- All exposed MCP tools run directly. There is no extra approval toggle.
- The window checks for updates in the background and shows an **Update** button in its header when a newer release exists — it can refresh Git installs in place or download and import the latest `unitypackage` automatically.

## Why This Project

- **`execute_code` First** — Optimized around one in-memory C# execution tool for rich editor/runtime orchestration. See [`execute_code`: In-Memory C# Execution](#execute_code-in-memory-c-execution) below for details.
- **Default Safety Checks** — `execute_code` now has persistent default-on safety toggles, including a stricter filesystem guard for clients that do not expose per-call arguments clearly
- **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 Need