ComfyUI Workflow Building Guide

API Format

ComfyUI workflows use a JSON format where each node is a key-value pair:

{
  "1": {
    "class_type": "KSampler",
    "inputs": {
      "seed": 42,
      "steps": 20,
      "cfg": 7.0,
      "sampler_name": "euler",
      "scheduler": "normal",
      "denoise": 1.0,
      "model": ["2", 0],
      "positive": ["3", 0],
      "negative": ["4", 0],
      "latent_image": ["5", 0]
    }
  }
}

• Keys are string node IDs (e.g., "1", "2")
• class_type is the ComfyUI node type name
• inputs contains parameters and connections
• Connections use the format ["source_node_id", output_index]

Common Node Chains

txt2img (text to image)

CheckpointLoaderSimple -> CLIPTextEncode (positive) -> KSampler -> VAEDecode -> SaveImage

img2img (image to image)

LoadImage -> VAEEncode -> KSampler (with denoise < 1.0) -> VAEDecode -> SaveImage

ControlNet

LoadImage -> ControlNetLoader + ControlNetApply -> feed into KSampler positive conditioning

LoRA Stacking

CheckpointLoaderSimple -> LoraLoader (chain multiple) -> KSampler

Key Nodes Reference

Node	Purpose	Key Inputs
CheckpointLoaderSimple	Load a model checkpoint	ckpt_name
CLIPTextEncode	Encode text prompt	text, clip
KSampler	Run diffusion sampling	model, positive, negative, latent_image, steps, cfg, seed
VAEDecode	Decode latent to image	samples, vae
VAEEncode	Encode image to latent	pixels, vae
SaveImage	Save output image	images, filename_prefix
LoadImage	Load input image	image (filename)
LoraLoader	Apply LoRA weights	model, clip, lora_name, strength_model, strength_clip
ControlNetLoader	Load ControlNet model	control_net_name
ControlNetApply	Apply ControlNet	conditioning, control_net, image, strength

Using the Workflow Tools

1. comfyui_create_workflow — Start from a template. Available templates can be listed with comfyui_list_workflows.
2. comfyui_modify_workflow — Add/remove nodes, change connections, update parameters on an existing workflow.
3. comfyui_validate_workflow — Check for missing connections, unknown node types, and potential issues.
4. comfyui_summarize_workflow — Get a human-readable description of what a workflow does.
5. comfyui_run_workflow — Submit a workflow for execution. Use wait=True to block until done.

Tips

• Always validate a workflow before running it.
• Use comfyui_list_nodes to check what node types are available on the connected ComfyUI instance.
• Use comfyui_get_node_info to get detailed input/output specs for a specific node type.
• Node IDs must be unique strings. When adding nodes, pick IDs that don't conflict with existing ones.
• The seed parameter controls reproducibility. Use a fixed seed for consistent results, or -1 for random.