中文版

UMG MCP for Unreal Engine 5.8

Build, inspect, refactor, and version UMG UI through AI agents and MCP tools.

Web Manual · Install · MCP Client · Fab Marketplace · Discord

UMG MCP turns Unreal Editor UMG work into explicit, reviewable tool calls. An AI agent can create widgets, update layout, wire Blueprint logic, edit materials, drive UMG animation, and round-trip UI files through JSON instead of relying on screenshots or fragile click automation.

The README is the front door. The step-by-step tutorials live in the deployed documentation site:

Why It Exists

Blueprint API Status (Transitional)

BlueCode now separates attention-compressed semantic reads from round-trip/debug evidence. Union writes support graph revisions, source maps, dry-run plans, LCS right-anchor insertion, safe append, and rollback on failure. It is still transitional: complete structured CFG recovery and editing for nested branches, loops, Sequence/Switch, latent nodes, and arbitrary irreducible graphs remains v2 work. Low-level node commands are compatibility execution primitives, not the BlueCode language.

Install

UMG MCP currently targets Unreal Engine 5.8 on Win64. The plugin descriptor in this package is set to EngineVersion: 5.8.0.

Option A: Fab Edition

Use this if you want the shortest install path and the in-editor workflow.

1. Open the Fab Marketplace listing.
2. Add the plugin to your Epic Games / Unreal Engine library.
3. Install it for Unreal Engine 5.8.
4. Open your project, enable UmgMcp, then restart the editor.
5. Open the plugin settings and configure your model provider. The web manual covers Google OAuth, Gemini API, ZhipuAI, and OpenAI-compatible endpoints.

Option B: Source Edition

Use this if you want to inspect the protocol, develop fixes, or integrate the plugin manually.

cd D:\UE5Project\YourProject
mkdir Plugins
cd Plugins
git clone https://github.com/winyunq/UnrealMotionGraphicsMCP.git UmgMcp

Then open the project in Unreal Engine 5.8 and allow Unreal Build Tool to compile the plugin. If you move the plugin between projects, keep the final folder name as UmgMcp unless you also update your MCP client configuration.

Connect An MCP Client

External MCP clients use the Python server under Resources/Python. Each Unreal Editor instance binds an OS-assigned local port and publishes it to the shared UmgMcp discovery registry. With one editor, the Python front end selects it automatically; with several editors, use list_umg_mcp_servers and connect_umg_mcp to choose the project.

Add this to the mcpServers section of your client settings, replacing the path with your own absolute plugin path:

{
  "mcpServers": {
    "UmgMcp": {
      "command": "uv",
      "args": [
        "run",
        "--directory",
        "D:\\UE5Project\\YourProject\\Plugins\\UmgMcp\\Resources\\Python",
        "UmgMcpServer.py"
      ]
    }
  }
}

Notes:

• The path must point to Resources/Python, not the repository root.
• On Windows JSON paths need escaped backslashes: D:\\Path\\To\\Project.
• If uv is missing, install it first or create the optional virtual environment below.

Optional local Python setup:

cd D:\UE5Project\YourProject\Plugins\UmgMcp\Resources\Python
uv venv
.\.venv\Scripts\activate
uv pip install "mcp[cli]>=1.4.1" fastmcp uvicorn fastapi "pydantic>=2.6.1" requests
python -c "import mcp, fastapi, pydantic, requests; print('deps ok')"

Verify The Setup

Run static protocol checks without opening a project:

cd D:\UE5Project\YourProject\Plugins\UmgMcp\Resources\Python
uv run python APITest\Umg_Widget_Protocol_Static_Check.py
uv run python APITest\Blueprint_MCP_Schema_Check.py
uv run python APITest\Material_Protocol_Static_Check.py
uv run python APITest\Animation_Protocol_Static_Check.py

Run an editor smoke test after Unreal Editor is open:

uv run python APITest\UE5_Editor_Imitation.py

If the editor-side test cannot connect, check that the plugin is enabled and use list_umg_mcp_servers to confirm its dynamically assigned endpoint is discoverable.

Documentation Map

What Agents Can Do

Example prompt for an MCP-capable agent:

Create /Game/UI/WBP_LoginPanel with a centered login card, email and password fields,
a primary submit button, and a subtle material background. Export the final widget JSON
and summarize which MCP tools changed the asset.

Videos

• Designing an RTS UI
• Recreating the UE5 editor
• Editing UMG inside the UMG editor
• Chatting with Gemini to edit a UMG file

Troubleshooting

Fab And Open Source

Core protocol improvements are intended to flow back to the open repository. If you report an issue from a project using the Fab package, include your UE version, plugin version, target asset path, and the failing MCP tool payload when possible.

Developer Program

Developers who contribute useful fixes, tests, documentation, or protocol examples can request Fab access for validation work. Open an issue or contact the maintainer with the contribution link and the scenario you want to test.

License

This repository is released under the MIT License.