io-ateliertech-comfyui-mcp 0.2.0
MCP server for ComfyUI workflow automation by IO-AtelierTech
Requires Python: >=3.10
Keywords: ai, claude, comfyui, image-generation, io-ateliertech, mcp, workflow

# Comfy MCP Server

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> MCP server for comprehensive ComfyUI workflow automation, management, and image generation.

## Overview

This server provides Claude Code (and other MCP clients) with full access to ComfyUI capabilities:

- **System monitoring**: Check server health, queue status, and history
- **Workflow execution**: Run saved workflows or execute custom workflow dicts
- **Workflow management**: Create, modify, save, and validate workflows
- **Node discovery**: List available nodes, models, and their parameters
- **Image generation**: Simple prompt-based generation or full workflow control

## Prerequisites

- [uv](https://docs.astral.sh/uv/) - Python package manager
- Running ComfyUI server (local or remote)
- Workflow files exported from ComfyUI (API format)

## Installation

```bash
# Install from source
git clone https://github.com/DanEscher98/io-ateliertech-comfyui-mcp.git
cd io-ateliertech-comfyui-mcp
uv sync
```

## Configuration

### Environment Variables

| Variable | Required | Default | Description |
|----------|----------|---------|-------------|
| `COMFY_URL` | No | `http://localhost:8188` | ComfyUI server URL |
| `COMFY_URL_EXTERNAL` | No | Same as COMFY_URL | External URL for image retrieval |
| `COMFY_WORKFLOWS_DIR` | No | - | Directory for API format workflows (execution) |
| `COMFY_WORKFLOWS_UI_DIR` | No | - | Directory for UI format workflows (editor) |
| `COMFY_WORKFLOW_JSON_FILE` | No | - | Default workflow file for `generate_image` |
| `PROMPT_NODE_ID` | No | - | Default prompt node ID for `generate_image` |
| `OUTPUT_NODE_ID` | No | - | Default output node ID |
| `OUTPUT_MODE` | No | `file` | Output mode: `file` (Image) or `url` (string URL) |
| `POLL_TIMEOUT` | No | `60` | Max seconds to wait for workflow (1-300) |
| `POLL_INTERVAL` | No | `1.0` | Seconds between status polls (0.1-10.0) |

### Example Configuration

```bash
export COMFY_URL=http://localhost:8188
export COMFY_WORKFLOWS_DIR=/path/to/workflows-api      # API format for execution
export COMFY_WORKFLOWS_UI_DIR=/path/to/workflows-ui    # UI format for editor
export COMFY_WORKFLOW_JSON_FILE=/path/to/workflows-api/default.json
export PROMPT_NODE_ID=6
export OUTPUT_NODE_ID=9
export OUTPUT_MODE=file
```

### Claude Desktop Config

```json
{
  "mcpServers": {
    "ComfyUI": {
      "command": "uv",
      "args": ["--directory", "/path/to/io-ateliertech-comfyui-mcp", "run", "io-ateliertech-comfyui-mcp"],
      "env": {
        "COMFY_URL": "http://localhost:8188",
        "COMFY_WORKFLOWS_DIR": "/path/to/workflows-api",
        "COMFY_WORKFLOWS_UI_DIR": "/path/to/workflows-ui",
        "COMFY_WORKFLOW_JSON_FILE": "/path/to/workflows-api/default.json",
        "PROMPT_NODE_ID": "6",
        "OUTPUT_NODE_ID": "9"
      }
    }
  }
}
```

## Available Tools

### System Tools

| Tool | Description |
|------|-------------|
| `get_system_stats()` | Get ComfyUI server health: version, memory, device info |
| `get_queue_status()` | Get current queue: running and pending jobs |
| `get_history(limit=10)` | Get recent generation history (1-100 entries) |
| `cancel_current(prompt_id=None)` | Interrupt current generation |
| `clear_queue(delete_ids=None)` | Clear queue or delete specific items |

### Discovery Tools

| Tool | Description |
|------|-------------|
| `list_nodes(filter=None)` | List available ComfyUI nodes (optional filter) |
| `get_node_info(node_name)` | Get detailed node info: inputs, outputs, parameters |
| `search_nodes(query)` | Search nodes by name, type, or category |
| `list_models(folder="checkpoints")` | List models in a folder |
| `list_model_folders()` | List available model folder types |
| `list_embeddings()` | List available embeddings |
| `list_extensions()` | List loaded extensions (custom node packs) |
| `refresh_nodes()` | Refresh cached node list from ComfyUI |

### Workflow Management Tools

| Tool | Description |
|------|-------------|
| `list_workflows()` | List available workflow files |
| `load_workflow(workflow_name)` | Load a workflow from file |
| `save_workflow(workflow, name, format="ui")` | Save workflow (format: "api" or "ui") |
| `create_workflow()` | Create an empty workflow structure |
| `add_node(workflow, node_id, class_type, inputs)` | Add a node to a workflow |
| `remove_node(workflow, node_id)` | Remove a node from a workflow |
| `update_node_input(workflow, node_id, input_name, value)` | Update a node's input |
| `validate_workflow(workflow)` | Validate workflow structure and node types |
| `convert_workflow_to_ui(workflow)` | Convert API format to UI/Litegraph format |
| `list_templates()` | List available workflow templates |
| `get_workflow_template(template_name)` | Get a pre-built workflow template |
| `generate_workflow_name(words=2)` | Generate random funny workflow name |

### Execution Tools

| Tool | Description |
|------|-------------|
| `generate_image(prompt)` | Generate image using default workflow (simple interface) |
| `run_workflow(workflow_name, inputs=None, output_node_id=None)` | Execute a saved workflow file |
| `execute_workflow(workflow, output_node_id)` | Execute an arbitrary workflow dict |
| `submit_workflow(workflow)` | Submit workflow without waiting (returns prompt_id) |
| `get_prompt_status(prompt_id)` | Get status of a submitted prompt |
| `get_result_image(prompt_id, output_node_id)` | Get result image from completed prompt |

## Workflow Formats

ComfyUI uses two workflow formats. Understanding the difference is critical:

| Format | Structure | Use Case | Directory |
|--------|-----------|----------|-----------|
| **API** | `{"node_id": {"class_type": "...", "inputs": {...}}}` | MCP execution, automation | `workflows-api/` |
| **UI** | `{"nodes": [...], "links": [...], "version": ...}` | ComfyUI editor only | `workflows-ui/` |

**IMPORTANT**:
- Only **API format** workflows can be executed via MCP (`run_workflow()`, `execute_workflow()`)
- **UI format** workflows are for loading/editing in the ComfyUI web editor
- The MCP server will reject UI format workflows with an error if you try to execute them

### Format Detection

The server automatically detects format by checking for `"nodes"` or `"version"` keys (UI format) vs `"class_type"` keys (API format).

## Creating, Validating, and Saving Workflows

### Recommended Workflow Process

```python
# 1. CREATE: Start with empty workflow or template
wf = create_workflow()
# Or use a template:
wf = get_workflow_template("fal-flux-dev")

# 2. BUILD: Add nodes with explicit connections
wf = add_node(wf, "1", "LoadImage", {"image": "input.jpg"})
wf = add_node(wf, "2", "LumaImageToVideoNode", {
    "prompt": "smooth camera motion",
    "model": "ray-2",
    "first_image": ["1", 0],  # Connect to node "1", output index 0
    "resolution": "1080p",
    "duration": "5s"
})
wf = add_node(wf, "3", "SaveVideo_fal", {
    "videos": ["2", 0],
    "filename_prefix": "output"
})

# 3. VALIDATE: Check structure and node types before saving
validation = validate_workflow(wf)
# Returns: {"valid": true/false, "errors": [...], "warnings": [...]}

# 4. SAVE: Choose format based on purpose
# For MCP execution (API format):
save_workflow(wf, "my-workflow", format="api")  # → workflows-api/my-workflow.json

# For ComfyUI editor (UI format):
save_workflow(wf, "my-workflow", format="ui")   # → workflows-ui/my-workflow.json
```

### Node Connections

Connections use the format `["source_node_id", output_index]`:

```python
# Connect node "1" output slot 0 to this input
wf = add_node(wf, "2", "CLIPTextEncode", {
    "text": "my prompt",
    "clip": ["1", 0]  # ← Connection to node "1", first output
})
```

### Discovering Node Parameters

Before adding a node, check its required inputs:

```python
# Find available nodes
nodes = list_nodes(filter="Luma")  # → ["LumaImageToVideoNode", ...]

# Get node details
info = get_node_info("LumaImageToVideoNode")
# Returns:
# {
#   "input": {
#     "required": {
#       "prompt": ["STRING", {...}],
#       "model": [["ray-2", "ray-flash-2"], {...}],
#       "first_image": ["IMAGE"],
#       ...
#     },
#     "optional": {...}
#   },
#   "output": ["VIDEO"],
#   ...
# }
```

### Validation Errors

Common validation issues:

| Error | Cause | Fix |
|-------|-------|-----|
| `Unknown node type` | Node class doesn't exist | Use `list_nodes()` to find correct name |
| `Missing required input` | Required input not provided | Check `get_node_info()` for required inputs |
| `Invalid connection` | Source node/output doesn't exist | Verify node IDs and output indices |
| `UI format detected` | Trying to execute UI format | Use API format or re-export from ComfyUI |

## Usage Examples

### Simple Image Generation

```python
# Using default workflow configuration
result = generate_image("a cyberpunk city at sunset")
```

### Run a Named Workflow

```python
# Execute saved workflow with custom inputs
result = run_workflow(
    "flux-dev.json",
    inputs={"6": {"text": "a forest landscape"}},
    output_node_id="9"
)
```

### Build and Execute Custom Workflow

```python
# 1. Create empty workflow
wf = create_workflow()

# 2. Add nodes
wf = add_node(wf, "1", "CheckpointLoaderSimple", {
    "ckpt_name": "flux-dev.safetensors"
})
wf = add_node(wf, "2", "CLIPTextEncode", {
    "text": "beautiful sunset over mountains",
    "clip": ["1", 1]  # Connect to checkpoint's CLIP output
})
wf = add_node(wf, "3", "KSampler", {
    "model": ["1", 0],
    "positive": ["2", 0],
    # ... other inputs
})

# 3. Validate before execution
validation = validate_workflow(wf)
if not validation.get("valid"):
    print(f"Errors: {validation.get('errors')}")

# 4. Execute
result = execute_workflow(wf, output_node_id="9")
```

### Async Workflow Submission

```python
# Submit without waiting
submission = submit_workflow(workflow)
prompt_id = submission["prompt_id"]

# Check status later
status = get_prompt_status(prompt_id)

# Get result when ready
if status["completed"]:
    image = get_result_image(prompt_id, "9")
```

### Discover Available Nodes

```python
# List all fal.ai nodes
nodes = list_nodes(filter="fal")

# Get details about a specific node
info = get_node_info("RemoteCheckpointLoader_fal")
```

### Using fal.ai Connector

The [ComfyUI-fal-Connector](https://github.com/badayvedat/ComfyUI-fal-Connector) enables cloud GPU inference via fal.ai.

```python
# 1. Verify fal.ai extension is loaded
extensions = list_extensions()
# Should include "ComfyUI-fal-Connector"

# 2. List available fal.ai nodes
fal_nodes = list_nodes(filter="fal")
# Returns: ["RemoteCheckpointLoader_fal", "StringInput_fal", "SaveImage_fal", ...]

# 3. Get node details
info = get_node_info("RemoteCheckpointLoader_fal")
# Shows available checkpoints: flux-dev, flux-schnell, sd3.5-large, etc.

# 4. Build a fal.ai workflow
wf = create_workflow()
wf = add_node(wf, "1", "RemoteCheckpointLoader_fal", {
    "ckpt_name": "flux-dev"
})
wf = add_node(wf, "2", "StringInput_fal", {
    "text": "a futuristic city at sunset, cyberpunk style"
})
wf = add_node(wf, "3", "CLIPTextEncode", {
    "text": ["2", 0],
    "clip": ["1", 1]
})
# ... add sampler, VAE decode, save image nodes

# 5. Execute on fal.ai cloud GPUs
result = execute_workflow(wf, output_node_id="9")
```

**Environment Setup:**
```bash
export FAL_KEY=your-fal-api-key
```

## Architecture

```
comfy_mcp_server/
├── __init__.py      # Entry point, FastMCP server
├── api.py           # HTTP helpers, ComfyUI API functions
├── models.py        # Pydantic models for type safety
├── settings.py      # Configuration with pydantic-settings
├── compat.py        # Version compatibility layer
└── tools/           # MCP tool implementations
    ├── system.py    # System monitoring tools
    ├── discovery.py # Node/model discovery
    ├── workflow.py  # Workflow management
    └── execution.py # Workflow execution
```

## Development

```bash
# Install dev dependencies
uv sync --all-extras

# Run linting
uv run ruff check src/

# Run tests (requires running ComfyUI)
uv run pytest tests/

# Format code
uv run ruff format src/
```

## ComfyUI API Coverage

Target: **ComfyUI 0.3.x - 0.4.x**

| API Endpoint | Method | Description | Status |
|--------------|--------|-------------|--------|
| `/prompt` | POST | Submit workflow for execution | ✅ Implemented |
| `/queue` | GET | View running/pending jobs | ✅ Implemented |
| `/queue` | POST | Clear queue / delete items | ✅ Implemented |
| `/history` | GET | View generation history | ✅ Implemented |
| `/history/{id}` | GET | Get specific job result | ✅ Implemented |
| `/history` | POST | Delete history entries | ⚠️ Partial |
| `/interrupt` | POST | Stop current generation | ✅ Implemented |
| `/object_info` | GET | List all available nodes | ✅ Implemented |
| `/object_info/{node}` | GET | Get node parameters/inputs | ✅ Implemented |
| `/models` | GET | List model folders | ✅ Implemented |
| `/models/{folder}` | GET | List models in folder | ✅ Implemented |
| `/system_stats` | GET | Server health/resources | ✅ Implemented |
| `/view` | GET | Retrieve generated images | ✅ Implemented |
| `/embeddings` | GET | List available embeddings | ✅ Implemented |
| `/extensions` | GET | List loaded extensions | ✅ Implemented |
| `/upload/image` | POST | Upload image for workflows | ❌ Not implemented |
| `/upload/mask` | POST | Upload mask for inpainting | ❌ Not implemented |
| `/free` | POST | Free VRAM/memory | ❌ Not implemented |
| `/api/userdata/*` | * | User data management | ❌ Not implemented |

### Implementation Notes

- **Partial**: History deletion is not fully exposed as a tool
- **Not implemented**: Image/mask upload, memory management, and user data APIs are planned for future releases

## Compatibility

- **MCP Server Version**: 0.2.0
- **Minimum ComfyUI**: 0.3.0
- **Maximum Tested ComfyUI**: 0.4.x
- **Python**: 3.10+

The server includes a compatibility layer that handles API differences between ComfyUI versions and provides graceful degradation.

## License

MIT License - see [LICENSE](LICENSE) file.

## Credits

Originally forked from [@lalanikarim/io-ateliertech-comfyui-mcp](https://github.com/lalanikarim/io-ateliertech-comfyui-mcp).