comfy-workflow-mcp

Run the workflows saved in a ComfyUI server as tools for any MCP agent (Claude Code, Claude Desktop, Cursor, your own agent).

Build and tune a workflow in the ComfyUI editor and save it. Agents can then list it, see its inputs, and run it with their own prompt, images and seed. Edit the workflow and save again: the next run uses the new version, because the saved file is loaded on every run.

Works with a local or remote ComfyUI, and with a vast.ai instance found from your API key.

Source-available, not open source. The code is public to read and evaluate. Using, copying, modifying or redistributing it needs written permission from the owner (jinsoo96); PlateerLab members have it within Plateer products. See LICENSE.

Tools

Inputs are addressed as <node id | title | class>.<input>:

{
  "name": "portrait.json",
  "set": {"Positive.text": "a red fox in the snow", "KSampler.seed": 7, "EmptyLatentImage.width": 1024},
  "images": {"Reference": "C:/pics/fox.png"},
  "enable": ["Turbo LoRA"],
  "wait_seconds": 25
}

A title wins over a class name, so give the nodes you want agents to touch a clear title in the editor (Positive, Reference). If a name matches more than one node, the error lists the ids to use instead. images takes a local file (uploaded for you) or a file name already on the server. enable / bypass switch nodes on or off for that run only. Seeds saved as "randomize" get a new value each run unless you set them.

Related MCP server: ComfyUI MCP Server

Install

pip install git+https://github.com/PlateerLab/comfy-workflow-mcp
# or from a checkout
pip install -e .

Python 3.10+. The only dependency is the mcp SDK; the ComfyUI client uses the standard library.

Configure

On vast.ai the ComfyUI template puts basic auth in front of the port: user vastai, password = the instance's Jupyter token. The server reads both from the vast.ai API, so the address and token stay right when you recreate the instance.

Claude Code / Claude Desktop

{
  "mcpServers": {
    "comfy": {
      "command": "comfy-workflow-mcp",
      "env": {"VAST_API_KEY": "...", "COMFY_DOWNLOAD_DIR": "D:/comfy_outputs"}
    }
  }
}

How it works

ComfyUI saves workflows in the editor format (nodes, positional widget values, numbered links). The /prompt endpoint needs the API format (named inputs). The server converts one into the other on every run, using the server's own /object_info to name the widgets, so any installed custom node works without a mapping table.

The conversion handles bypassed nodes (links pass through), muted nodes, notes, Reroute, legacy PrimitiveNode values, the seed "control after generate" slot, and widgets converted to inputs. API-format files saved in the workflows folder run as they are. Subgraphs and group nodes are not supported yet: unpack them in the editor and save again.

The editor workflow is sent along with each run, so every output PNG opens as the exact canvas that made it.

Security

• The vast.ai API key can control your whole account. This server only reads the instance list (GET /instances); it never creates, stops or deletes anything. The key and the instance token are not logged or returned by any tool.

• Agents can run any saved workflow and read the server's model and input lists. Point the server at a ComfyUI you are happy to share with the agent.

Development

pip install -e ".[dev]"
pytest

The tests cover the conversion offline with a hand-made /object_info.

License

Source-available, all rights reserved: LICENSE. Reading, evaluating and citing are allowed; any other use needs written permission from the owner (jinsoo96, wlstn010203@gmail.com, or an issue on this repository). PlateerLab/comfy-workflow-mcp is the origin; jinsoo96/js-comfy-workflow-mcp mirrors it automatically.