comfyui-mcp-server-node

This is improved node.js version of Joe Norton's python project (https://github.com/joenorton/comfyui-mcp-server).

A lightweight MCP (Model Context Protocol) server that bridges AI agents (like Cursor, Claude, etc.) with a local ComfyUI instance. It enables AI agents to generate and iteratively refine images, audio, and video through conversational tool calls.

Features

• Image Generation: Generate images using Stable Diffusion through ComfyUI
• Audio Generation: Generate audio/music using AceStep workflow
• Workflow System: PARAM_* placeholder system for easy workflow customization
• Asset Management: Track, view, and manage generated assets
• Job Management: Monitor queue, check job status, cancel jobs
• Configuration: List available models

Quick Start

Option 1: Via npx (for MCP clients)

No local clone needed. Add to your MCP client configuration (Cursor, Claude, etc.):

"comfyui": {
  "command": "npx",
  "args": ["-y", "comfyui-mcp-server-node"],
  "env": {
    "COMFYUI_URL": "http://localhost:8188",
    "COMFY_MCP_WORKFLOW_DIR": "/path/to/workflows",
    "COMFY_MCP_ASSET_TTL_HOURS": "24"
  }
}

Note: ComfyUI must be running at COMFYUI_URL before the MCP client connects.

Option 2: Local development

git clone https://github.com/yar3333/comfyui-mcp-server-node.git
cd comfyui-mcp-server-node
npm install
npm run build

Then start:

| Command | Mode | | ------------- | ----------------------- | | npm start | stdio (for MCP clients) | | npm run dev | stdio with ts-node |

Configuration

Environment Variables

| Variable | Description | Default | | --------------------------- | --------------------------- | ----------------------- | | COMFYUI_URL | ComfyUI base URL | http://localhost:8188 | | COMFY_MCP_WORKFLOW_DIR | Path to workflow directory | ./workflows | | COMFY_MCP_ASSET_TTL_HOURS | Asset time-to-live in hours | 24 |

API Tools

Generation Tools

| Tool | Description | | ------------- | ---------------------------------------------------- | | <workflows> | Available workflows automatically published as tools | | regenerate | Regenerate a previously generated asset |

Viewing Tools

| Tool | Description | | ------------ | ------------------------------------- | | view_image | View a generated image inline in chat |

Job Management Tools

| Tool | Description | | -------------------- | --------------------------------------------- | | get_queue_status | Get current queue status from ComfyUI | | get_job | Get job status by prompt_id | | wait_for_job | Wait for a job to complete with timeout | | list_assets | List generated assets with optional filtering | | get_asset_metadata | Get full metadata for a specific asset | | cancel_job | Cancel a running job by prompt_id |

Configuration Tools

| Tool | Description | | ------------------------ | ----------------------------------------------------------- | | list_checkpoint_models | List available checkpoint models from ComfyUI | | list_unet_models | List available UNet models in standard (safetensors) format | | list_unet_gguf_models | List available UNet models in GGUF format |

Workflow Tools

| Tool | Description | | ---------------- | -------------------------------------------------- | | list_workflows | List available workflows in the workflow directory | | run_workflow | Run a specific workflow with parameter overrides |

Workflow System

Workflows are stored as JSON files in the workflows/ directory. The system automatically discovers workflows and exposes them as MCP tools. Parameters are defined using the PARAM_* placeholder system:

• PARAM_INT_SEED - Integer parameter for seed
• PARAM_FLOAT_CFG - Float parameter for CFG scale
• PARAM_STR_SAMPLER_NAME - String parameter for sampler name
• PARAM_PROMPT - String parameter for prompt

Test

Prerequisites: ComfyUI running at http://localhost:8188, server built and started.

# Run the test client
npx ts-node test_client.ts

# With custom prompt
npx ts-node test_client.ts -p "a beautiful sunset over mountains"

# Run unit tests
npm test

Project Structure

comfyui-mcp-server-node/
├── src/
│   ├── comfyui_client.ts        # HTTP client for ComfyUI API
│   ├── asset_processor.ts       # Image processing utilities
│   ├── server.ts                # Main entry point
│   ├── models/                  # Data models
│   │   ├── asset.ts
│   │   └── workflow.ts
│   ├── managers/                # Manager classes
│   │   ├── workflow_manager.ts
│   │   └── asset_registry.ts
│   └── tools/                   # MCP tool implementations
│       ├── helpers.ts
│       ├── generation.ts
│       ├── asset.ts
│       ├── job.ts
│       ├── configuration.ts
│       └── workflow.ts
├── workflows/                   # Workflow JSON files
├── test_client.ts               # Test client
├── package.json
├── tsconfig.json
└── README.md

Changelog

v2.x.x

• add list_checkpoint_models tool
• add list_unet_models tool
• add list_unet_gguf_models tool
• remove http mode (stdio looks enough)
• remove list_models tool
• remove publish system (caused confusion for AI agents; use custom output node instead)
• remove default parameters (caused confusion for AI agents; use regular PARAM_* instead)
• remove output folder setting (use custom output node instead; for example: https://gist.github.com/kevinjwesley-Collab/a548ee5e6244ebf905f0669e1d7d4958)

v1.x.x

• add wait_for_job tool

License

MIT

Author

@yar3333