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comfyui-workflow-editor-mcp

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 — with a graph-based workflow editor for safe, validated modifications.

Features

  • Workflow Graph Editor: Safe, validated editing of ComfyUI workflows as directed graphs

    • Add, remove, replace, and insert nodes with automatic type-checking and cycle detection

    • Search available node types from the ComfyUI /object_info catalog

    • Validate workflows before execution (type mismatches, cycles, orphans, missing inputs)

    • Compare workflows, convert between API and frontend formats, generate workflows from templates

Related MCP server: ComfyUI MCP

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-workflow-editor-mcp"],
  "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-workflow-editor-mcp.git
cd comfyui-workflow-editor-mcp
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 Graph Editor Tools

Graph-based tools for safe, validated editing of ComfyUI workflows. All mutations validate type compatibility, detect cycles, and report orphan nodes.

Tool

Description

get_workflow_graph

Get workflow structure as a graph with nodes, links, chains

search_node_types

Search available node types from the ComfyUI catalog

get_node_info

Get detailed schema for a node type (inputs, outputs, defaults)

add_node

Add a node with validation (type-check, cycle detection)

remove_node

Remove a node, reporting affected connections and orphans

connect_nodes

Create a connection between node outputs and inputs

disconnect_node_input

Disconnect an input from a node

set_node_input

Change a primitive input value on a node

insert_node

Insert a node into an existing link (break-and-reconnect)

replace_node

Replace a node type, preserving compatible connections

validate_workflow

Full validation: types, cycles, orphans, missing inputs

find_connection_path

Find the dependency path between two nodes

build_basic_workflow

Generate a workflow from a template (txt2img, img2img, etc.)

convert_workflow_format

Convert between ComfyUI API format and frontend JSON format

diff_workflows

Compare two workflows, showing added/removed/modified nodes

Workflow Graph Editor

The workflow graph editor represents ComfyUI workflows as directed graphs, enabling safe modifications with automatic validation.

How It Works

  • WorkflowGraph — in-memory graph representation of a workflow (nodes, connections, execution order)

  • NodeTypesCatalog — cached catalog of available node types loaded from ComfyUI's /object_info API

  • Validation rules — every mutation is checked against the same rules ComfyUI uses internally:

Check

Description

Required inputs

All mandatory inputs must be provided

Link targets

Links reference existing nodes and valid slot indices

Type compatibility

Output types match input type expectations (supports unions and wildcards)

Cycle detection

DFS-based cycle detection prevents invalid dependency graphs

Orphan detection

Nodes unreachable from any output node are flagged

Output node check

At least one output node (SaveImage, SaveAudio, etc.) must exist

Built-in Templates

build_basic_workflow supports the following templates:

Template

Description

Nodes

txt2img_basic

Basic text-to-image

CheckpointLoader, 2×CLIPTextEncode, EmptyLatent, KSampler, VAEDecode, SaveImage

img2img_basic

Image-to-image

CheckpointLoader, LoadImage, VAEEncode, 2×CLIPTextEncode, KSampler, VAEDecode, SaveImage

txt2img_controlnet

Text-to-image + ControlNet

Basic + ControlNetLoader, LoadImage, ControlNetApply

txt2img_sdxl

SDXL text-to-image

CheckpointLoader, CLIPTextEncode (4×), EmptyLatent, KSampler (2×), VAEDecode, SaveImage

upscale_basic

Upscale pipeline

CheckpointLoader, ImageUpscaleWithModel, VAEEncode, KSampler, VAEDecode, SaveImage

Format Conversion

ComfyUI uses two JSON formats:

  • API format — flat {node_id: NodeData} map used by the backend (what the MCP server works with)

  • Frontend format — structured {nodes, links, groups} format exported from the ComfyUI UI

Use convert_workflow_format to convert between them.

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-workflow-editor-mcp/
├── 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
│   │   ├── workflow_graph.ts    # WorkflowGraph — in-memory graph representation
│   │   └── node_types.ts        # NodeTypeSchema and related interfaces
│   ├── managers/                # Manager classes
│   │   ├── workflow_manager.ts
│   │   ├── asset_registry.ts
│   │   └── node_types_catalog.ts # NodeTypesCatalog — cached /object_info catalog
│   └── tools/                   # MCP tool implementations
│       ├── helpers.ts
│       ├── generation.ts
│       ├── asset.ts
│       ├── job.ts
│       ├── configuration.ts
│       ├── workflow.ts          # list_workflows, run_workflow
│       └── workflow_edit.ts     # Graph editor tools (add, remove, connect, validate, etc.)
├── workflows/                   # Workflow JSON files
├── test_client.ts               # Test client
├── package.json
├── tsconfig.json
└── README.md

License

MIT

Author

@yar3333

A
license - permissive license
Not graded
quality - not tested
B
maintenance

Maintenance

Maintainers
Response time
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Releases (12mo)
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