AnkleBreaker Unity MCP Plugin
A Unity package with a local editor bridge: an agent drives scenes, prefabs, builds and tests over MCP
- 257 ★ on the repository
- Last commit
Broad access
Why this level
- The agent gets code execution tools and edits scenes, scripts and assets with the authority of the editor process
- The same routes start project builds and tests, which change files on disk
- Several agents in one editor can make conflicting edits: the queue only orders requests
Install
- Works in
Manual install
git clone https://github.com/AnkleBreaker-Studio/unity-mcp-server.git
cd unity-mcp-server
npm installThe companion Node.js server; without it an agent cannot reach the bridge. Client setup details are in the server repository.
Access and checks
How we reviewBroad accessThe tool can change data, run commands or handle secrets.
- The agent gets code execution tools and edits scenes, scripts and assets with the authority of the editor process
- The same routes start project builds and tests, which change files on disk
- Several agents in one editor can make conflicting edits: the queue only orders requests
This is third-party code. Review the repository files before installing.
What it does
AnkleBreaker Unity MCP Plugin is the Unity side of the AnkleBreaker MCP server. The UPM package starts a local HTTP bridge inside the editor, and a Node.js server passes agent commands to it. The bridge registers 338 editor routes: scenes and objects, components, prefabs, materials, animation, terrain, particles, audio, UI, lighting, navigation, builds, profiling and scripts. The bridge is built for several agents and several projects at once. Each editor has its own listener, queue and identity, and requests from different agents wait in a per-agent queue served round-robin. For multiplayer work it adds control of Multiplayer Play Mode scenarios and players and ParrelSync clone discovery. In the editor the package adds an MCP status dropdown to the main toolbar and a Dashboard window with the queue, agent cards, HTTP activity and an action history. Supported changes are recorded as named undo groups. Optional integrations cover ProBuilder, UMA, Amplify Shader Editor, Shader Graph, VFX Graph, Input System and Memory Profiler, and the agent discovers their tools by calling `unity_list_advanced_tools`.
Who it is for. For Unity game developers who want to hand editor work to an agent and, when needed, run several agents on one project.
Good fit when
- An agent should build a scene in an open editor: place objects, set up materials and lighting, edit components
- Several agents work on the project and their requests to one editor must queue without conflicts
- You need to run EditMode and PlayMode tests and get results page by page, keeping the job ID
- You are debugging a networked game and want to control Multiplayer Play Mode scenarios and ParrelSync clones from an agent
- You want to see which actions and requests each agent made and undo the supported changes
Not a fit when
- You work in Godot, Unreal or another engine: the package runs only in the Unity editor 2021.3.18f1 or newer
- You want a single install with no Node.js: working with an agent needs the separate MCP server, and the Unity package alone does not replace it
- The editor is open on a shared or untrusted machine: code execution tools get the authority of the editor process
- You need every change to be reversible: undo works only for commands that register Unity undo operations
Example request
List my running Unity editors, select my prototype and inspect its scene and compilation errors before making any changesMCP
- Transport
- stdio
- Authentication
- not required
Limitations
The package works only together with the AnkleBreaker Node.js server and an MCP client. It needs Unity 2021.3.18f1 or newer, and uGUI and Unity Test Framework come in as dependencies. Package and server versions advance independently and need not match. Installing from `#main` gives the latest changes, while published npm packages and version tags may lag behind.
The bridge listens on the loopback address only and uses port 7890 by default. The port can change after an editor restart, so rediscover the project and port. Heavy Unity operations occupy the editor main thread, and the queue does not make them non-blocking. Undo does not cover every command, and a timeout does not cancel work that has already started. The license is non-standard, so read the LICENSE file before commercial use. UMA 2 runtime behavior is unverified.
How to disable. Open Window, Package Manager in Unity and remove the AnkleBreaker Unity MCP Plugin package, then delete the unity entry from the MCP client config. You can check the bridge state and queue in the Dashboard window before removal.
FAQ
How do I install the AnkleBreaker Unity MCP Plugin?
In Unity open Window, Package Manager, Add package from git URL and paste `https://github.com/AnkleBreaker-Studio/unity-mcp-plugin.git#main`. Then open Window, AB Unity MCP, Dashboard, check the bridge state and install the separate Node server.
How does the plugin differ from the AnkleBreaker server?
The plugin lives inside Unity and executes commands in the editor: queue, history, integrations. The Node.js server talks to your MCP client and routes each request to the right editor. You need both.
How do several agents share one editor?
Each agent has its own queue and requests are served round-robin, with reads grouped. In one pass the editor runs one write or up to five classified reads. The queue orders requests but does not resolve conflicting edits by different agents.
Which port does the bridge use and what about several projects?
Port 7890 by default, and several editors claim different ports. Call `unity_list_instances`, select the project and pass the discovered port on concurrent requests rather than relying on the value after a restart.
What can I undo after an agent edits the project?
Supported synchronous writes get named undo groups, and `unity_undo_history` shows the history. Commands that do not register Unity undo and filesystem changes cannot be reverted this way.
Discussion
No questions or reviews yet.
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Comparison with similar tools
Cards that share the main search query, and how they differ.
| Tool | Official | Authentication | Repository stars | Main difference |
|---|---|---|---|---|
| AnkleBreaker Unity MCP Plugin (this card) | no | not required | 257 | |
| Unity MCP Server | no | not required | 542 | the Node.js server for the MCP client; the Unity package is installed separately |
| MCP for Unity | no | not required | 15,943 | an MCP for Unity with a different bridge and tool set |
| AI Game Developer (Unity MCP) | no | not required | 4,631 | a Unity plugin with its own MCP server, skills and CLI |
README in short
The document presents the package as the editor half of a workflow for multiple projects, agents and multiplayer iteration. It includes recorded demos of scene building, a diagram of how the bridge works, performance measurements and a description of the monitoring dashboard. The measured improvements are tied to specific workloads, as the author notes.