KitWright Unity MCP

KitWright MCP for Unity

The Most Advanced MCP Server for Unity Editor

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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 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.

Demo — AI searches project prefabs and builds a city scene through MCP tools. Watch HD MP4 .

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#upm

💡 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:

openupm add com.kitwright.unity.mcp

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

{

"scopedRegistries": [ { "name": "OpenUPM", "url": "https://package.openupm.com", "scopes": [ "com.kitwright" ] } ], "dependencies": { "com.kitwright.unity.mcp": "1.0.2" } }

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:

Claude Code / Claude Desktop

{

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

Cursor

{

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

LM Studio

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.

{

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

VS Code

{

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

Trae

{

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

Kiro

{

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

Codex

[mcp_servers.kitwright]

url = "http://127.0.0.1:8765/"

Windsurf

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

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 exposes a compact set of 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 every tool exposed. A profile only shortens the tool list for the client; it is not an access control, since any client can switch it with set_tool_profile and execute_code is in every profile. Restrict a tool through your client's tool-approval prompt.
• 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.
• 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 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 Needed — core exposes a compact high-signal toolset; full exposes every tool
• 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

• Built-in Tools — Scene editing, assets, scripts, play mode control, screenshots and screenshot diffing, performance analysis, prompts, resources, structured object location, SerializedObject-based component and project-settings editing, animator authoring, compound uGUI controls, editor-state inspection, menu-item fallback, and editor automation across 57 modules. Full list: TOOLS.md
• Structured Returns + `instanceId` Chaining — Tools return {success, message, data} JSON with stable instanceId fields so agents can chain by_id calls reliably instead of re-resolving by name
• `IKitWrightCommand` for `execute_code` — New snippet template with auto-Undo (ctx.RegisterObjectCreation / ctx.RegisterObjectModification / ctx.DestroyObject), structured logs (ctx.Log/LogWarning/LogError), and a tracked changelog returned to the agent
• 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 — The MCP Window surfaces new releases and either re-pulls the Git package or auto-imports the latest unitypackage
• Integrations Tab — Detects Hot Reload, Memory Profiler, Addressables, Input System, Timeline, URP, and Test Fram