Unreal MCP Bridge

Drive Unreal Engine 5 from any AI assistant over the Model Context Protocol. An MCP server (this repo) exposes the editor as tools, speaking to Unreal's built-in Remote Control API — no custom plugin or in-engine code needed.

MCP client (Claude Desktop / Cursor / Muse / ...)
   --stdio-->  server/unreal_mcp_server.py
   --HTTP 127.0.0.1:30010-->  UE Remote Control API  -->  editor

Part of the bridge family: blender-mcp-bridge shares the same tool names and conventions.

What you can do with it

• "Spawn a cube at (300, 0, 100)" → spawn_actor

• "List everything in the level" → list_actors

• "Move that light up 500 units" → set_actor_transform

• "Find all static meshes named 'Wall'" → search_assets

• "Set that actor's mobility to movable" → set_property

• Anything else → call_function (the raw power tool)

Related MCP server: unreal-engine-mcp

Setup

1. Enable Remote Control in Unreal

1. In the UE editor: Edit → Plugins → search "Remote Control API" → Enable it (restart the editor).

2. Open the editor console ( ` key) and run:

   WebControl.StartServer

   To make it automatic, run once: WebControl.EnableServerOnStartup

3. Verify: open http://127.0.0.1:30010/remote/info in a browser — you should see JSON, not a connection error.

The editor must be open with a level loaded while you use the bridge. EditorActorSubsystem tools (spawn/list/delete actors) need the editor — they don't work in a packaged game.

2. Install the MCP server

python -m venv .venv && source .venv/bin/activate   # Windows: .venv\Scripts\activate
pip install -r requirements.txt

Windows users: extract the release zip and double-click run_server.bat (it creates the venv, installs deps, and starts the server for a sanity check).

3. Point your AI client at it

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "unreal": {
      "command": "/absolute/path/to/.venv/bin/python",
      "args": ["/absolute/path/to/server/unreal_mcp_server.py"]
    }
  }
}

Cursor: Settings → MCP → Add Server → same command/args.

Muse CLI: Muse mcp add unreal -- /absolute/path/to/.venv/bin/python /absolute/path/to/server/unreal_mcp_server.py

Then ask it to run ping_unreal — if it reports the RC server info, you're live.

Shared-server mode (optional)

python server/unreal_mcp_server.py --http --port 8001
# serves MCP at http://127.0.0.1:8001/mcp

One server, many clients. If Unreal runs on a different host/port: --rc-host / --rc-port (or env UNREAL_RC_HOST / UNREAL_RC_PORT).

Tools

Unreal conventions (the AI must know these)

• Units are centimeters. location=[0, 0, 500] is 5 meters up.

• Rotation is Pitch/Yaw/Roll in degrees — not XYZ euler.

• Objects are addressed by path, e.g. /Game/Maps/MyMap.MyMap:PersistentLevel.MyActor.

• Blueprint classes need the _C suffix: /Game/Blueprints/BP_Cube.BP_Cube_C. Native classes look like /Script/Engine.StaticMeshActor.

Limitations (honest)

• No viewport screenshots. The Remote Control API doesn't expose one. Use UE's HighResShot console command manually when you need a visual check.

• Actor tools target the editor. Packaged builds only expose what your game's Remote Control presets expose.

• Function parameter shapes follow UE's reflection; when in doubt, ask the AI to get_actor_info / describe first — it lists exact function signatures.

Troubleshooting

• "cannot reach Unreal Remote Control at 127.0.0.1:30010" → editor isn't open, the Remote Control API plugin isn't enabled, or you didn't run WebControl.StartServer.

• Port already in use → another UE instance (or something else) holds 30010.

• Empty/missing actors → make sure a level is loaded in the editor.

Security

The bridge can call any exposed UE function, including spawning and deleting actors. It binds to localhost only. Never forward port 30010 to a network.

Project layout

server/unreal_rc_client.py   # stdlib-only HTTP client for the RC API
server/unreal_mcp_server.py   # the MCP server (FastMCP tools over stdio)
tests/test_rc_client.py       # client tests against a mock RC server
tests/test_mcp_server.py      # tool registration + RC call-shape tests