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UE5-UMG-MCP 🤖📄

A Version-Controlled AI-Assisted UMG Workflow

Demo Designed A RTS UI

Demo Recreating the UE5 editor

Demo Recreating the UE5 editor in UMG editor

Chat with Gemini 3 to editor the UMG file

🚀 Quick Start

This guide covers the two-step process to install the UmgMcp plugin and connect it to your Gemini CLI.

• Prerequisite: Unreal Engine 5.6 or newer.

1. Install the Plugin

1. Navigate to your project's Plugins folder: YourProject/Plugins/ (create it if it doesn't exist).

2. Clone the repository directly into this directory:

   git clone https://github.com/winyunq/UnrealMotionGraphicsMCP.git UmgMcp
   

3. Restart the Unreal Editor. This allows the engine to detect and compile the new plugin.

2. Connect the Gemini CLI

Tell Gemini how to find and launch the MCP server.

1. Edit your settings.json file (usually located at C:\Users\YourUsername\.gemini\).

2. Add the tool definition to the mcpServers object.

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

   IMPORTANT: You must replace the path with the correct absolute path to the Resources/Python folder from the cloned repository on your machine.

That's it! When you start the Gemini CLI, it will automatically launch the MCP server in the background.

Testing the Connection

After restarting your Gemini CLI and opening your Unreal project, you can test the connection by calling any tool function:

  cd Resources/Python/APITest
  python UE5_Editor_Imitation.py

Python Environment (Optional)

The plugin's Python environment is managed by uv. In most cases, it should work automatically. If you encounter issues related to Python dependencies (e.g., uv command not found or module import errors), you can manually set up the environment:

1. Navigate to the directory: cd YourUnrealProject/Plugins/UmgMcp/Resources/Python
2. Run the setup:

   uv venv
   .\.venv\Scripts\activate
   uv pip install -e .
   

English

This project provides a powerful, command-line driven workflow for managing Unreal Engine's UMG UI assets. By treating human-readable .json files as the sole Source of Truth, it fundamentally solves the challenge of versioning binary .uasset files in Git.

Inspired by tools like blender-mcp, this system allows developers, UI designers, and AI assistants to interact with UMG assets programmatically, enabling true Git collaboration, automated UI generation, and iteration.

Prompt Manager

A visual web tool for configuring system instructions, tool descriptions, and user prompt templates.

Features

1. System Instruction Editor: Modify the global instructions for the AI context.
2. Tool Management:
   • Enable/Disable: Toggle specific MCP tools on or off. Disabled tools are not registered with the MCP server, effectively compressing the context window to prevent AI distraction.
   • Edit Descriptions: Customize tool descriptions (prompts) to better suit your workflow.
3. User Templates (Prompts): Add reusable prompt templates for quick access by the MCP client.

How to Run

Execute the following command in your Python environment:

python Resources/Python/PromptManager/server.py

The browser will automatically open http://localhost:8085.

Usage Tips

Prompts are crucial for AI tool effectiveness. Use the Prompt Manager to tailor the AI's behavior:

• One-Click Deployment Mode: If you want the AI to focus solely on generating UI from design, disable all tools except apply_layout and export_umg_to_json.
• Tutor Mode: If you want the AI to guide you without making changes, keep only read-only tools (e.g., get_widget_tree, get_widget_schema).
• Context Optimization: For models with smaller context windows, disable tools you aren't currently using to improve speed and accuracy.

Contributions of effective prompt configurations are welcome!

AI Authorship & Disclaimer

This project has been developed with significant assistance from Gemini, an AI. As such:

• Experimental Nature: This is an experimental project. Its reliability is not guaranteed.
• Commercial Use: Commercial use is not recommended without thorough independent validation and understanding of its limitations.
• Disclaimer: Use at your own risk. The developers and AI are not responsible for any consequences arising from its use.

Current Technical Architecture Overview

The system now primarily relies on the UE5_UMG_MCP plugin for communication between external clients (like this CLI) and the Unreal Engine Editor.

Architecture Diagram:

flowchart LR
    subgraph "Local Execution Environment"
        CLI["Gemini CLI"] --"StdIO (JSON-RPC)"--> PY["Python (UmgMcpServer.py)"]
    end

    subgraph "Unreal Engine 5"
        PY --"TCP Socket (JSON)"--> TCP["UmgMcpBridge (C++)"]
        TCP --> API["Unreal API / UMG"]
    end

API Status

UMG Blueprint API Status (New)

UMG Sequencer API Status

Troubleshooting & Known Issues

[!WARNING] Startup Order is Critical We have observed that the TCP connection handshake can be confusing. You MUST launch the Unreal Engine 5 project FIRST, wait for it to initialize, and THEN launch the Gemini CLI.

If you launch the CLI first, the Python server may fail to connect correctly or enter a retry loop that results in connection failures or "success-on-kill" behavior. The UE5 Server acts as the Listener; it must be ready before the Client connects.