Comfy (Stable Diffusion) MCP server

This MCP server allows you to generate images based on prompts by connecting to a remote ComfyUI server. It leverages the FastMCP framework to handle communication between your local system and the ComfyUI instance that performs the actual image generation.

Prerequisites

Before you can use the ComfyMCP server, you'll need:

• uv - A Python package and project manager
• A workflow file exported from ComfyUI

Install the required packages with:

uvx mcp[cli]

Configuration

The server requires several environment variables to function properly:

• COMFY_URL - URL of your ComfyUI server
• COMFY_WORKFLOW_JSON_FILE - Absolute path to your exported ComfyUI workflow file
• PROMPT_NODE_ID - ID of the text prompt node in your workflow
• OUTPUT_NODE_ID - ID of the output node that produces the final image
• OUTPUT_MODE - Either url or file depending on how you want to receive images

Example configuration:

export COMFY_URL=http://your-comfy-server-url:port
export COMFY_WORKFLOW_JSON_FILE=/path/to/the/comfyui_workflow_export.json
export PROMPT_NODE_ID=6  # use your actual node ID
export OUTPUT_NODE_ID=9  # use your actual node ID
export OUTPUT_MODE=file

Optional Ollama Integration

If you want to use Ollama for prompt generation:

export OLLAMA_API_BASE=http://localhost:11434  # or your Ollama URL
export PROMPT_LLM=llama3  # or your preferred Ollama model

Running the Server

Start the server with:

uvx comfy-mcp-server

Claude Desktop Integration

You can integrate the server with Claude Desktop by adding it to your Claude config:

{
  "mcpServers": {
    "Comfy MCP Server": {
      "command": "/path/to/uvx",
      "args": [
        "comfy-mcp-server"
      ],
      "env": {
        "COMFY_URL": "http://your-comfy-server-url:port",
        "COMFY_WORKFLOW_JSON_FILE": "/path/to/the/comfyui_workflow_export.json",
        "PROMPT_NODE_ID": "6",
        "OUTPUT_NODE_ID": "9",
        "OUTPUT_MODE": "file"
      }
    }
  }
}

Server Functions

Image Generation

The server provides a generate_image function that:

1. Validates environment variables
2. Loads the workflow template
3. Submits your prompt to the ComfyUI server
4. Polls for completion
5. Returns the generated image

Prompt Generation

If you've configured Ollama integration, the generate_prompt function can create detailed image generation prompts from simple topic descriptions.

How to install this MCP server

For Claude Code

To add this MCP server to Claude Code, run this command in your terminal:

claude mcp add-json "Comfy-MCP-Server" '{"command":"/path/to/uvx","args":["comfy-mcp-server"],"env":{"COMFY_URL":"http://your-comfy-server-url:port","COMFY_WORKFLOW_JSON_FILE":"/path/to/the/comfyui_workflow_export.json","PROMPT_NODE_ID":"6","OUTPUT_NODE_ID":"9","OUTPUT_MODE":"file"}}'

See the official Claude Code MCP documentation for more details.

For Cursor

There are two ways to add an MCP server to Cursor. The most common way is to add the server globally in the ~/.cursor/mcp.json file so that it is available in all of your projects.

If you only need the server in a single project, you can add it to the project instead by creating or adding it to the .cursor/mcp.json file.

Adding an MCP server to Cursor globally

To add a global MCP server go to Cursor Settings > Tools & Integrations and click "New MCP Server".

When you click that button the ~/.cursor/mcp.json file will be opened and you can add your server like this:

{
    "mcpServers": {
        "Comfy MCP Server": {
            "command": "/path/to/uvx",
            "args": [
                "comfy-mcp-server"
            ],
            "env": {
                "COMFY_URL": "http://your-comfy-server-url:port",
                "COMFY_WORKFLOW_JSON_FILE": "/path/to/the/comfyui_workflow_export.json",
                "PROMPT_NODE_ID": "6",
                "OUTPUT_NODE_ID": "9",
                "OUTPUT_MODE": "file"
            }
        }
    }
}

Adding an MCP server to a project

To add an MCP server to a project you can create a new .cursor/mcp.json file or add it to the existing one. This will look exactly the same as the global MCP server example above.

How to use the MCP server

Once the server is installed, you might need to head back to Settings > MCP and click the refresh button.

The Cursor agent will then be able to see the available tools the added MCP server has available and will call them when it needs to.

You can also explicitly ask the agent to use the tool by mentioning the tool name and describing what the function does.

For Claude Desktop

To add this MCP server to Claude Desktop:

1. Find your configuration file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

2. Add this to your configuration file:

{
    "mcpServers": {
        "Comfy MCP Server": {
            "command": "/path/to/uvx",
            "args": [
                "comfy-mcp-server"
            ],
            "env": {
                "COMFY_URL": "http://your-comfy-server-url:port",
                "COMFY_WORKFLOW_JSON_FILE": "/path/to/the/comfyui_workflow_export.json",
                "PROMPT_NODE_ID": "6",
                "OUTPUT_NODE_ID": "9",
                "OUTPUT_MODE": "file"
            }
        }
    }
}

3. Restart Claude Desktop for the changes to take effect