Content
# MCP Unity Editor (Game Engine)
[](https://modelcontextprotocol.io/introduction)
[](https://unity.com/releases/editor/archive)
[](https://nodejs.org/en/download/)
[](https://github.com/CoderGamester/mcp-unity/stargazers)
[](https://github.com/CoderGamester/mcp-unity/commits/main)
[](https://opensource.org/licenses/MIT)
| [🇺🇸English](README.md) | [🇨🇳简体中文](README_zh-CN.md) | [🇯🇵日本語](README-ja.md) |
|----------------------|---------------------------------|----------------------|
```
,/(/. *(/,
*/(((((/. *((((((*.
.*((((((((((/. *((((((((((/.
./((((((((((((((/ *((((((((((((((/,
,/(((((((((((((/*. */(((((((((((((/*.
,%%#((/((((((* ,/(((((/(#&@@(
,%%##%%##((((((/*. ,/((((/(#&@@@@@@(
,%%######%%##((/(((/*. .*/(((//(%@@@@@@@@@@@(
,%%####%#(%%#%%##((/((((((((//#&@@@@@@&@@@@@@@@(
,%%####%( /#%#%%%##(//(#@@@@@@@%, #@@@@@@@(
,%%####%( *#%###%@@@@@@( #@@@@@@@(
,%%####%( #%#%@@@@, #@@@@@@@(
,%%##%%%( #%#%@@@@, #@@@@@@@(
,%%%#* #%#%@@@@, *%@@@(
., ,/##*. #%#%@@@@, ./&@#* *`
,/#%#####%%#/, #%#%@@@@, ,/&@@@@@@@@@&\.
`*#########%%%%###%@@@@@@@@@@@@@@@@@@&*´
`*%%###########%@@@@@@@@@@@@@@&*´
`*%%%######%@@@@@@@@@@&*´
`*#%%##%@@@@@&*´
`*%#%@&*´
███╗ ███╗ ██████╗██████╗ ██╗ ██╗███╗ ██╗██╗████████╗██╗ ██╗
████╗ ████║██╔════╝██╔══██╗ ██║ ██║████╗ ██║██║╚══██╔══╝╚██╗ ██╔╝
██╔████╔██║██║ ██████╔╝ ██║ ██║██╔██╗ ██║██║ ██║ ╚████╔╝
██║╚██╔╝██║██║ ██╔═══╝ ██║ ██║██║╚██╗██║██║ ██║ ╚██╔╝
██║ ╚═╝ ██║╚██████╗██║ ╚██████╔╝██║ ╚████║██║ ██║ ██║
╚═╝ ╚═╝ ╚═════╝╚═╝ ╚═════╝ ╚═╝ ╚═══╝╚═╝ ╚═╝ ╚═╝
```
MCP Unity is an implementation of the Model Context Protocol for Unity Editor, allowing AI assistants to interact with your Unity projects. This package provides a bridge between Unity and a Node.js server that implements the MCP protocol, enabling AI agents like Cursor, Windsurf, Claude Code, Codex CLI, GitHub Copilot, and Google Antigravity to execute operations within the Unity Editor.
## Features
### IDE Integration - Package Cache Access
MCP Unity provides automatic integration with VSCode-like IDEs (Visual Studio Code, Cursor, Windsurf, Google Antigravity) by adding the Unity `Library/PackedCache` folder to your workspace. This feature:
- Improves code intelligence for Unity packages
- Enables better autocompletion and type information for Unity packages
- Helps AI coding assistants understand your project's dependencies
### MCP Server Tools
The following tools are available for manipulating and querying Unity scenes and GameObjects via MCP:
- `execute_menu_item`: Executes Unity menu items (functions tagged with the MenuItem attribute)
> **Example prompt:** "Execute the menu item 'GameObject/Create Empty' to create a new empty GameObject"
- `select_gameobject`: Selects game objects in the Unity hierarchy by path or instance ID
> **Example prompt:** "Select the Main Camera object in my scene"
- `update_gameobject`: Updates a GameObject's core properties (name, tag, layer, active/static state), or creates the GameObject if it does not exist
> **Example prompt:** "Set the Player object's tag to 'Enemy' and make it inactive"
- `update_component`: Updates component fields on a GameObject or adds it to the GameObject if it does not contain the component
> **Example prompt:** "Add a Rigidbody component to the Player object and set its mass to 5"
- `add_package`: Installs new packages in the Unity Package Manager
> **Example prompt:** "Add the TextMeshPro package to my project"
- `run_tests`: Runs tests using the Unity Test Runner
> **Example prompt:** "Run all the EditMode tests in my project"
- `capture_performance_snapshot`: Captures a short memory snapshot, plus frame timing when Unity is in Play Mode
> **Example prompt:** "Capture a 5 second performance snapshot while the game is running"
- `send_console_log`: Send a console log to Unity
> **Example prompt:** "Send a console log to Unity Editor"
- `add_asset_to_scene`: Adds an asset from the AssetDatabase to the Unity scene
> **Example prompt:** "Add the Player prefab from my project to the current scene"
- `create_prefab`: Creates a prefab with optional MonoBehaviour script and serialized field values
> **Example prompt:** "Create a prefab named 'Player' from the 'PlayerController' script"
- `create_scene`: Creates a new scene and saves it to the specified path
> **Example prompt:** "Create a new scene called 'Level1' in the Scenes folder"
- `load_scene`: Loads a scene by path or name, with optional additive loading
> **Example prompt:** "Load the MainMenu scene"
- `delete_scene`: Deletes a scene by path or name and removes it from Build Settings
> **Example prompt:** "Delete the old TestScene from my project"
- `get_gameobject`: Gets detailed information about a specific GameObject including all components
> **Example prompt:** "Get the details of the Player GameObject"
- `click_ui`: Clicks a Unity UI GameObject by hierarchy path or instance ID using EventSystem pointer events
> **Example prompt:** "Click the Continue button in the active popup"
- `scroll_ui`: Scrolls a Unity UI ScrollRect by normalized position/delta and can dispatch a scroll event
> **Example prompt:** "Scroll the month picker down by 0.1"
- `set_ui_input_text`: Sets text on Unity UI InputField, TMP_InputField, Text, or TMP_Text components
> **Example prompt:** "Set the date of birth input text to 04/11/1982"
- `invoke_component_method`: Invokes a method on a component attached to a GameObject, with optional non-public access
> **Example prompt:** "Invoke OnDateSelectionComplete on DateSelectionReciever with 1982-11-04"
- `get_console_logs`: Retrieves logs from the Unity console with pagination support
> **Example prompt:** "Show me the last 20 error logs from the Unity console"
- `recompile_scripts`: Recompiles all scripts in the Unity project
> **Example prompt:** "Recompile scripts in my Unity project"
- `save_scene`: Saves the current active scene, with optional Save As to a new path
> **Example prompt:** "Save the current scene" or "Save the scene as 'Assets/Scenes/Level2.unity'"
- `discard_open_scene_changes`: Reloads dirty open scenes from disk, discarding unsaved changes silently (no *Scene(s) Have Been Modified* modal). Use before quit / scene switch / `run_tests` when a scene was unintentionally dirtied — e.g. an `[ExecuteAlways]` MonoBehaviour spawning children after a domain reload. Refuses with errcode `cannot_discard_unsaved_scene` if any loaded scene has no asset path on disk.
> **Example prompt:** "Discard unsaved changes in the open scenes so I can switch scenes without the save dialog"
- `save_open_scenes`: Saves every dirty open scene to disk silently (no *Scene(s) Have Been Modified* modal). Refuses with errcode `cannot_save_unsaved_scene` if any dirty scene has no asset path — use `save_scene` with an explicit `scenePath` in that case.
> **Example prompt:** "Save all open scenes before I exit the editor"
- `get_scene_info`: Gets information about the active scene including name, path, dirty state, and all loaded scenes
> **Example prompt:** "What scenes are currently loaded in my project?"
- `unload_scene`: Unloads a scene from the hierarchy (does not delete the scene asset)
> **Example prompt:** "Unload the UI scene from the hierarchy"
- `duplicate_gameobject`: Duplicates a GameObject in the scene with optional renaming and reparenting
> **Example prompt:** "Duplicate the Enemy prefab 5 times and rename them Enemy_1 through Enemy_5"
- `delete_gameobject`: Deletes a GameObject from the scene
> **Example prompt:** "Delete the old Player object from the scene"
- `reparent_gameobject`: Changes the parent of a GameObject in the hierarchy
> **Example prompt:** "Move the HealthBar object to be a child of the UI Canvas"
- `move_gameobject`: Moves a GameObject to a new position (local or world space)
> **Example prompt:** "Move the Player object to position (10, 0, 5) in world space"
- `rotate_gameobject`: Rotates a GameObject to a new rotation (local or world space, Euler angles or quaternion)
> **Example prompt:** "Rotate the Camera 45 degrees on the Y axis"
- `scale_gameobject`: Scales a GameObject to a new local scale
> **Example prompt:** "Scale the Enemy object to twice its size"
- `set_transform`: Sets position, rotation, and scale of a GameObject in a single operation
> **Example prompt:** "Set the Cube's position to (0, 5, 0), rotation to (0, 90, 0), and scale to (2, 2, 2)"
- `create_material`: Creates a new material with specified shader and saves it to the project
> **Example prompt:** "Create a red material called 'EnemyMaterial' using the URP Lit shader"
- `assign_material`: Assigns a material to a GameObject's Renderer component
> **Example prompt:** "Assign the 'EnemyMaterial' to the Enemy GameObject"
- `modify_material`: Modifies properties of an existing material (colors, floats, textures)
> **Example prompt:** "Change the color of 'EnemyMaterial' to blue and set metallic to 0.8"
- `get_material_info`: Gets detailed information about a material including shader and all properties
> **Example prompt:** "Show me all the properties of the 'PlayerMaterial'"
- `batch_execute`: Executes multiple tool operations in a single batch request, reducing round-trips and enabling atomic operations with optional rollback on failure
> **Example prompt:** "Create 10 empty GameObjects named Enemy_1 through Enemy_10 in a single batch operation"
- `detect_unity_modal` *(Windows-only)*: Detects native Win32 modal dialogs blocking the Unity Editor main thread (read-only). Useful when the WebSocket is connected but Unity stops responding to tool calls.
> **Example prompt:** "Unity stopped responding — check if a native modal dialog is blocking it"
- `dismiss_unity_modal` *(Windows-only)*: Dismisses a native Win32 modal by exact button name (case-sensitive). Idempotent — returns `dialog_already_dismissed` if the dialog is gone.
> **Example prompt:** "Click 'Don't Save' on the Unity scene-modified dialog"
### Modal dialog tools (Windows-only)
When Unity's main thread is blocked by a native modal (e.g. *Scene(s) Have Been Modified*), MCP requests time out because the WebSocket bridge cannot execute Unity-side code. The `detect_unity_modal` and `dismiss_unity_modal` tools run **out-of-process** via PowerShell + UIAutomation against the OS, not against Unity.
Resolution priority for the target Unity process: explicit `targetPid` → explicit `projectPath` → cwd-fallback (when `cwd/ProjectSettings` exists) → `UNITY_PID` env hint → single-Unity heuristic. Ambiguity returns `multiple_unity_processes_require_explicit_target` with the candidate list.
Only Win32 dialogs (window class `#32770`) are supported in MVP — IMGUI / `EditorUtility.DisplayDialog` modals return `unsupported_dialog_kind`. UAC mismatch (Unity elevated, Node not) returns `permission_denied_uac_mismatch`.
**Optional opt-in env var** for read-only timeout-path diagnostics:
- `MCP_UNITY_DETECT_MODALS_ON_TIMEOUT=true` — when a Unity request times out, the bridge spawns the modal helper for ≤500ms and attaches `details.modalDiagnostics` to the rejected error. Failure-tolerant: detection failure never masks the original timeout. Default off.
Live UIAutomation interaction with native dialogs cannot run in standard headless CI (Windows session 0 isolation). Unit tests mock the spawn boundary; an interactive Windows runner is required for end-to-end verification.
### Dirty scene preflight for Play Mode and tests
`enter_play_mode` and `run_tests` accept `dirtyScenePolicy` to decide what to do when loaded scenes have unsaved changes before Unity would otherwise show a *Scene(s) Have Been Modified* prompt.
Available policies:
- `report` (default): proceed and include a warning in `preflight.warnings`; does not save or discard changes.
- `fail`: refuse with `errcode="dirty_scenes_blocked"` and a `dirtyScenes` payload. This is recommended for CI/headless callers.
- `save`: save each dirty loaded scene; refuses with `cannot_save_unsaved_scene` if any dirty scene has no asset path.
- `discard`: reload scenes from disk and discard dirty state; requires `dirtyScenePolicyScope`.
`dirtyScenePolicyScope` is required only for `discard` when dirty scenes are present:
- `active`: reloads the active scene from disk; additive scenes are detached and reported in `preflight.warnings`.
- `loaded`: reloads the active scene, then reopens loaded additive scenes by path; refuses with `cannot_discard_unsaved_scene` if any loaded scene has no asset path.
The same `save` / `discard` behavior is also exposed as standalone tools — `save_open_scenes` and `discard_open_scene_changes` — for cases where the caller wants to resolve dirty state outside of a Play Mode or test entry point.
### MCP Server Resources
- `unity://menu-items`: Retrieves a list of all available menu items in the Unity Editor to facilitate `execute_menu_item` tool
> **Example prompt:** "Show me all available menu items related to GameObject creation"
- `unity://scenes-hierarchy`: Retrieves a list of all game objects in the current Unity scene hierarchy
> **Example prompt:** "Show me the current scenes hierarchy structure"
- `unity://gameobject/{id}`: Retrieves detailed information about a specific GameObject by instance ID or object path in the scene hierarchy, including all GameObject components with it's serialized properties and fields
> **Example prompt:** "Get me detailed information about the Player GameObject"
- `unity://logs`: Retrieves a list of all logs from the Unity console
> **Example prompt:** "Show me the recent error messages from the Unity console"
- `unity://packages`: Retrieves information about installed and available packages from the Unity Package Manager
> **Example prompt:** "List all the packages currently installed in my Unity project"
- `unity://assets`: Retrieves information about assets in the Unity Asset Database
> **Example prompt:** "Find all texture assets in my project"
- `unity://tests/{testMode}`: Retrieves information about tests in the Unity Test Runner
> **Example prompt:** "List all available tests in my Unity project"
## Requirements
- Unity 6 or later - to [install the server](#install-server)
- Node.js 18 or later - to [start the server](#start-server)
- npm 9 or later - to [debug the server](#debug-server)
## Codex Plugin
This repository can also be installed as a Codex plugin. The plugin manifest lives in `.codex-plugin/plugin.json` and registers the local MCP server through `.mcp.json`.
The plugin launcher starts `Server~/build/index.js`. On first run, it installs `Server~` npm dependencies and builds the TypeScript server if needed, keeping all setup output on stderr so MCP stdio remains clean.
> [!NOTE]
> **Project Paths with Spaces**
>
> MCP Unity supports project paths containing spaces. However, if you experience connection issues, try moving your project to a path without spaces as a troubleshooting step.
>
> **Examples:**
> - ✅ **Recommended:** `C:\Users\YourUser\Documents\UnityProjects\MyAwesomeGame`
> - ✅ **Supported:** `C:\Users\Your User\Documents\Unity Projects\My Awesome Game`
## <a name="install-server"></a>Installation
Installing this MCP Unity Server is a multi-step process:
### Step 1: Install Node.js
> To run MCP Unity server, you'll need to have Node.js 18 or later installed on your computer:
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Windows</span></summary>
1. Visit the [Node.js download page](https://nodejs.org/en/download/)
2. Download the Windows Installer (.msi) for the LTS version (recommended)
3. Run the installer and follow the installation wizard
4. Verify the installation by opening PowerShell and running:
```bash
node --version
```
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">macOS</span></summary>
1. Visit the [Node.js download page](https://nodejs.org/en/download/)
2. Download the macOS Installer (.pkg) for the LTS version (recommended)
3. Run the installer and follow the installation wizard
4. Alternatively, if you have Homebrew installed, you can run:
```bash
brew install node@18
```
5. Verify the installation by opening Terminal and running:
```bash
node --version
```
</details>
### Step 2: Install Unity MCP Server package via Unity Package Manager
1. Open the Unity Package Manager (Window > Package Manager)
2. Click the "+" button in the top-left corner
3. Select "Add package from git URL..."
4. Enter: `https://github.com/CoderGamester/mcp-unity.git`
5. Click "Add"
### Step 3: Configure AI LLM Client
<details open>
<summary><span style="font-size: 1.1em; font-weight: bold;">Option 1: Configure using Unity Editor</span></summary>
1. Open the Unity Editor
2. Navigate to Tools > MCP Unity > Server Window
3. Click on the "Configure" button for your AI LLM client as shown in the image below
4. Confirm the configuration installation with the given popup
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Option 2: Configure Manually</span></summary>
Open the MCP configuration file of your AI client and add the MCP Unity server configuration:
> Replace `ABSOLUTE/PATH/TO` with the absolute path to your MCP Unity installation or just copy the text from the Unity Editor MCP Server window (Tools > MCP Unity > Server Window).
**For JSON-based clients** (Cursor, Windsurf, Claude Code, GitHub Copilot, etc.):
```json
{
"mcpServers": {
"mcp-unity": {
"command": "node",
"args": [
"ABSOLUTE/PATH/TO/mcp-unity/Server~/build/index.js"
]
}
}
}
```
**For Codex CLI** (`~/.codex/config.toml`):
```toml
[mcp_servers.mcp-unity]
command = "node"
args = ["ABSOLUTE/PATH/TO/mcp-unity/Server~/build/index.js"]
```
</details>
## <a name="start-server"></a>Start Unity Editor MCP Server
1. Open the Unity Editor
2. Navigate to Tools > MCP Unity > Server Window
3. Click "Start Server" to start the WebSocket server
4. Open your AI Coding IDE (e.g. Cursor, Windsurf, Claude Code, Codex CLI, GitHub Copilot, Google Antigravity, etc.) and start executing Unity tools
> When the AI client connects to the WebSocket server, it will automatically show in the green box in the window
## Optional: Set WebSocket Port
By default, the WebSocket server runs on port '8090'. You can change this port in two ways:
1. Open the Unity Editor
2. Navigate to Tools > MCP Unity > Server Window
3. Change the "WebSocket Port" value to your desired port number
4. Unity will setup the system environment variable UNITY_PORT to the new port number
5. Restart the Node.js server
6. Click again on "Start Server" to reconnect the Unity Editor web socket to the Node.js MCP Server
## Optional: Set Timeout
By default, the timeout between the MCP server and the WebSocket is 10 seconds.
You can change depending on the OS you are using:
1. Open the Unity Editor
2. Navigate to Tools > MCP Unity > Server Window
3. Change the "Request Timeout (seconds)" value to your desired timeout seconds
4. Unity will setup the system environment variable UNITY_REQUEST_TIMEOUT to the new timeout value
5. Restart the Node.js server
6. Click again on "Start Server" to reconnect the Unity Editor web socket to the Node.js MCP Server
> [!TIP]
> The timeout between your AI Coding IDE (e.g., Claude Desktop, Cursor IDE, Windsurf IDE) and the MCP Server depends on the IDE.
## Optional: Allow Remote MCP Bridge Connections
By default, the WebSocket server binds to 'localhost'. To allow MCP bridge connections from other machines:
1. Open the Unity Editor
2. Navigate to Tools > MCP Unity > Server Window
3. Enable the "Allow Remote Connections" checkbox
4. Unity will bind the WebSocket server to '0.0.0.0' (all interfaces)
5. Restart the Node.js server to apply the new host configuration
6. Set the environment variable UNITY_HOST to your Unity machine's IP address when running the MCP bridge remotely: `UNITY_HOST=192.168.1.100 node server.js`
## <a name="debug-server"></a>Debugging the Server
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Building the Node.js Server</span></summary>
The MCP Unity server is built using Node.js . It requires to compile the TypeScript code to JavaScript in the `build` directory.
In case of issues, you can force install it in by:
1. Open the Unity Editor
2. Navigate to Tools > MCP Unity > Server Window
3. Click on "Force Install Server" button
If you want to build it manually, you can follow these steps:
1. Open a terminal/PowerShell/Command Prompt
2. Navigate to the Server directory:
```bash
cd ABSOLUTE/PATH/TO/mcp-unity/Server~
```
3. Install dependencies:
```bash
npm install
```
4. Build the server:
```bash
npm run build
```
5. Run the server:
```bash
node build/index.js
```
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Debugging with MCP Inspector</span></summary>
Debug the server with [@modelcontextprotocol/inspector](https://github.com/modelcontextprotocol/inspector):
- Powershell
```powershell
npx @modelcontextprotocol/inspector node Server~/build/index.js
```
- Command Prompt/Terminal
```cmd
npx @modelcontextprotocol/inspector node Server~/build/index.js
```
Don't forget to shutdown the server with `Ctrl + C` before closing the terminal or debugging it with the [MCP Inspector](https://github.com/modelcontextprotocol/inspector).
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Enable Console Logs</span></summary>
1. Enable logging on your terminal or into a log.txt file:
- Powershell
```powershell
$env:LOGGING = "true"
$env:LOGGING_FILE = "true"
```
- Command Prompt/Terminal
```cmd
set LOGGING=true
set LOGGING_FILE=true
```
</details>
## Frequently Asked Questions
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">What is MCP Unity?</span></summary>
MCP Unity is a powerful bridge that connects your Unity Editor environment to AI assistants LLM tools using the Model Context Protocol (MCP).
In essence, MCP Unity:
- Exposes Unity Editor functionalities (like creating objects, modifying components, running tests, etc.) as "tools" and "resources" that an AI can understand and use.
- Runs a WebSocket server inside Unity and a Node.js server (acting as a WebSocket client to Unity) that implements the MCP. This allows AI assistants to send commands to Unity and receive information back.
- Enables you to use natural language prompts with your AI assistant to perform complex tasks within your Unity project, significantly speeding up development workflows.
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Why use MCP Unity?</span></summary>
MCP Unity offers several compelling advantages for developers, artists, and project managers:
- **Accelerated Development:** Automate repetitive tasks, generate boilerplate code, and manage assets using AI prompts. This frees up your time to focus on creative and complex problem-solving.
- **Enhanced Productivity:** Interact with Unity Editor features without needing to manually click through menus or write scripts for simple operations. Your AI assistant becomes a direct extension of your capabilities within Unity.
- **Improved Accessibility:** Allows users who are less familiar with the deep intricacies of the Unity Editor or C# scripting to still make meaningful contributions and modifications to a project through AI guidance.
- **Seamless Integration:** Designed to work with various AI assistants and IDEs that support MCP, providing a consistent way to leverage AI across your development toolkit.
- **Extensibility:** The protocol and the toolset can be expanded. You can define new tools and resources to expose more of your project-specific or Unity's functionality to AI.
- **Collaborative Potential:** Facilitates a new way of collaborating where AI can assist in tasks traditionally done by team members, or help in onboarding new developers by guiding them through project structures and operations.
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">How does MCP Unity compare with the upcoming Unity 6.2 AI features?</span></summary>
Unity 6.2 is set to introduce new built-in AI tools, including the previous Unity Muse (for generative AI capabilities like texture and animation generation) and Unity Sentis (for running neural networks in Unity runtime). As Unity 6.2 is not yet fully released, this comparison is based on publicly available information and anticipated functionalities:
- **Focus:**
- **MCP Unity:** Primarily focuses on **Editor automation and interaction**. It allows external AI (like LLM-based coding assistants) to *control and query the Unity Editor itself* to manipulate scenes, assets, and project settings. It's about augmenting the *developer's workflow* within the Editor.
- **Unity 6.2 AI:**
- Aims at in-Editor content creation (generating textures, sprites, animations, behaviors, scripts) and AI-powered assistance for common tasks, directly integrated into the Unity Editor interface.
- A fine-tuned model to ask any question about Unity's documentation and API structure, with customized examples more accurate to Unity's environment.
- Adds the functionality to run AI model inference, allowing developers to deploy and run pre-trained neural networks *within your game or application* for features like NPC behavior, image recognition, etc.
- **Use Cases:**
- **MCP Unity:** "Create a new 3D object, name it 'Player', add a Rigidbody, and set its mass to 10." "Run all Play Mode tests." "Ask to fix the error on the console log." "Execute the custom menu item 'Prepare build for iOS' and fix any errors that may occur."
- **Unity 6.2 AI:** "Generate a sci-fi texture for this material." "Update all trees position in the scene to be placed inside of terrain zones tagged with 'forest'." "Create a walking animation for this character." "Generate 2D sprites to complete the character." "Ask details about the error on the console log."
- **Complementary, Not Mutually Exclusive:**
MCP Unity and Unity's native AI tools can be seen as complementary. You might use MCP Unity with your AI coding assistant to set up a scene or batch-modify assets, and then use Unity AI tools to generate a specific texture, or to create animations, or 2D sprites for one of those assets. MCP Unity provides a flexible, protocol-based way to interact with the Editor, which can be powerful for developers who want to integrate with a broader range of external AI services or build custom automation workflows.
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">What MCP hosts and IDEs currently support MCP Unity?</span></summary>
MCP Unity is designed to work with any AI assistant or development environment that can act as an MCP client. The ecosystem is growing, but current known integrations or compatible platforms include:
- Cursor
- Windsurf
- Claude Desktop
- Claude Code
- Codex CLI
- GitHub Copilot
- Google Antigravity
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Can I extend MCP Unity with custom tools for my project?</span></summary>
Yes, absolutely! One of the significant benefits of the MCP Unity architecture is its extensibility.
- **In Unity (C#):** You can create new C# classes that inherit from `McpToolBase` (or a similar base for resources) to expose custom Unity Editor functionality. These tools would then be registered in `McpUnityServer.cs`. For example, you could write a tool to automate a specific asset import pipeline unique to your project.
- **In Node.js Server (TypeScript):** You would then define the corresponding TypeScript tool handler in the `Server/src/tools/` directory, including its Zod schema for inputs/outputs, and register it in `Server/src/index.ts`. This Node.js part will forward the request to your new C# tool in Unity.
This allows you to tailor the AI's capabilities to the specific needs and workflows of your game or application.
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Is MCP Unity free to use?</span></summary>
Yes, MCP Unity is an open-source project distributed under the MIT License. You are free to use, modify, and distribute it according to the license terms.
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Why am I unable to connect to MCP Unity?</span></summary>
- Ensure the WebSocket server is running (check the Server Window in Unity)
- Send a console log message from MCP client to force a reconnection between MCP client and Unity server
- Change the port number in the Unity Editor MCP Server window. (Tools > MCP Unity > Server Window)
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Why won't the MCP Unity server start?</span></summary>
- Check the Unity Console for error messages
- Ensure Node.js is properly installed and accessible in your PATH
- Verify that all dependencies are installed in the Server directory
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Why do I get a connection failed error when running Play Mode tests?</span></summary>
The `run_tests` tool returns the following response:
```
Error:
Connection failed: Unknown error
```
This error occurs because the bridge connection is lost when the domain reloads upon switching to Play Mode. The workaround is to turn off **Reload Domain** in **Edit > Project Settings > Editor > "Enter Play Mode Settings"**.
</details>
<details>
<summary><span style="font-size: 1.1em; font-weight: bold;">Why do some clients fail with <code>KeyError: 'position'</code> during tool initialization?</span></summary>
Some MCP clients may fail while parsing tool schemas when they contain local JSON pointer references such as `#/properties/position`.
MCP Unity avoids this by registering transform tool inputs (`set_transform`, `move_gameobject`, `rotate_gameobject`, `scale_gameobject`) with fresh nested vector schemas per field, so the generated schema does not rely on local `#/properties/...` references.
If you still see this error:
- update your MCP client to the latest version,
- rebuild the Node server (`cd Server~ && npm run build`),
- confirm your package version includes this compatibility fix.
</details>
## Troubleshooting: WSL2 (Windows 11) networking
When running the MCP (Node.js) server inside WSL2 while Unity runs on Windows 11, connecting to `ws://localhost:8090/McpUnity` may fail with `ECONNREFUSED`.
Cause: WSL2 and Windows have separate network namespaces — `localhost` inside WSL2 does not point to the Windows host. By default, Unity listens on `localhost:8090`.
### Solution 1 — Enable WSL2 Mirrored mode networking (preferred)
- Windows 11: Settings → System → For developers → WSL → Enable “Mirrored mode networking”.
- Or via `.wslconfig` (then run `wsl --shutdown` and reopen WSL):
```ini
[wsl2]
networkingMode=mirrored
```
After enabling, `localhost` is shared between Windows and WSL2, so the default config (`localhost:8090`) works.
### Solution 2 — Point the Node client to the Windows host
Set in your WSL shell before starting the MCP client:
```bash
# Use the Windows host IP detected from resolv.conf
export UNITY_HOST=$(grep -m1 nameserver /etc/resolv.conf | awk '{print $2}')
```
With this, `Server~/src/unity/mcpUnity.ts` will connect to `ws://$UNITY_HOST:8090/McpUnity` instead of `localhost` (it reads `UNITY_HOST`, and may also honor a `Host` in `ProjectSettings/McpUnitySettings.json` if present).
### Solution 3 — Allow remote connections from Unity
- Unity: Tools → MCP Unity → Server Window → enable “Allow Remote Connections” (Unity binds to `0.0.0.0`).
- Ensure Windows Firewall allows inbound TCP on your configured port (default 8090).
- From WSL2, connect to the Windows host IP (see Solution 2) or to `localhost` if mirrored mode is enabled.
> [!NOTE]
> Default port is `8090`. You can change it in the Unity Server Window (Tools → MCP Unity → Server Window). The value maps to `McpUnitySettings` and is persisted in `ProjectSettings/McpUnitySettings.json`.
#### Validate connectivity
```bash
npm i -g wscat
# After enabling mirrored networking
wscat -c ws://localhost:8090/McpUnity
# Or using the Windows host IP
wscat -c ws://$UNITY_HOST:8090/McpUnity
```
## Running Tests
### C# Tests (Unity)
Run tests using Unity's Test Runner:
1. Open Unity Editor
2. Navigate to Window > General > Test Runner
3. Select "EditMode" tab
4. Click "Run All" to execute all tests
### TypeScript Tests (Server)
Run tests using Jest:
```bash
cd Server~
npm test
```
To run tests in watch mode:
```bash
npm run test:watch
```
## Support & Feedback
If you have any questions or need support, please open an [issue](https://github.com/CoderGamester/mcp-unity/issues) on this repository or alternative you can reach out on:
- Linkedin: [](https://www.linkedin.com/in/miguel-tomas/)
- Discord: gamester7178
- Email: game.gamester@gmail.com
## Contributing
Contributions are welcome! Please feel free to submit a Pull Request or open an Issue with your request.
**Commit your changes** following the [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/) format.
## License
This project is under [MIT License](LICENSE.md)
## Acknowledgements
- [Model Context Protocol](https://modelcontextprotocol.io)
- [Unity Technologies](https://unity.com)
- [Node.js](https://nodejs.org)
- [WebSocket-Sharp](https://github.com/sta/websocket-sharp)
