ComfyUI MCP Server

ComfyUI MCP Server

1. Overview

• A server implementation for integrating ComfyUI with MCP.
• ⚠️ IMPORTANT: This server requires a running ComfyUI server.
  • You must either host your own ComfyUI server,
  • or have access to an existing ComfyUI server address.

2. Debugging

2.1 ComfyUI Debugging

2.2 MCP Debugging

3. Installation and Configuration

3.1 ComfyUI Configuration

• Edit src/.env to set ComfyUI host and port:
  COMFYUI_HOST=localhost COMFYUI_PORT=8188

3.2 Adding Custom Workflows

• To add new tools, place your workflow JSON files in the workflows directory and declare them as new tools in the system.

4. Built-in Tools

• text_to_image
  • Returns only the URL of the generated image.
  • To get the actual image:
    • Use the download_image tool, or
    • Access the URL directly in your browser.
• download_image
  • Downloads images generated by other tools (like text_to_image) using the image URL.
• run_workflow_with_file
  • Run a workflow by providing the path to a workflow JSON file.
    # You should ask to agent like this. Run comfyui workflow with text_to_image.json
  • example image of CursorAI
• run_workflow_with_json
  • Run a workflow by providing the workflow JSON data directly.
    # You should ask to agent like this. Run comfyui workflow with this { "3": { "inputs": { "seed": 156680208700286, "steps": 20, ... (workflow JSON example) }

5. How to Run

5.1 Using UV (Recommended)

• Example mcp.json:
  { "mcpServers": { "comfyui": { "command": "uv", "args": [ "--directory", "PATH/MCP/comfyui", "run", "--with", "mcp", "--with", "websocket-client", "--with", "python-dotenv", "mcp", "run", "src/server.py:mcp" ] } } }

5.2 Using Docker

• Downloading images to a local folder with download_image may be difficult since the Docker container does not share the host filesystem.
• When using Docker, consider:
  1. Set RETURN_URL=false in .env to receive image data as bytes.
  2. Set COMFYUI_HOST in .env to the appropriate address (e.g., host.docker.internal or your server's IP).
  3. Note: Large image payloads may exceed response limits when using binary data.

5.2.1 Build Docker Image

5.2.2 Using Existing Images

Also you can use prebuilt image.

5.2.3 Using SSE Transport

1. Run the SSE server with Docker:
   docker run -i --rm -p 8001:8000 overseer66/mcp-comfyui-sse
2. Configure mcp.json (change localhost to your IP or domain if needed):
   { "mcpServers": { "comfyui": { "url": "http://localhost:8001/sse" } } }

NOTE: When adding new workflows as tools, you need to rebuild and redeploy the Docker images to make them available.