debug

A command guide for diagnosing failed ComfyUI workflows. ComfyUI is a visual system for building image-generation pipelines from connected processing steps called nodes.

In plain words
What is it for?
Use it to inspect the latest or a named workflow execution, identify the failing node and traceback, check matching system logs, and suggest a fix.
Why use it?
It gathers the failed execution, error details, logs, and node information so the failure can be traced to a specific step.

Command

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/artokun/comfyui-mcp/debug
Clone the repo
git clone --depth 1 https://github.com/artokun/comfyui-mcp
Per session 9 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 920 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00009 $0.00920
Opus 5 $0.00005 $0.00460
Sonnet 5 $0.00002 $0.00184
Haiku 4.5 $0.00001 $0.00092

Measured 2d ago against content hash 31f82a9175bd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

debug scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

  • debug — 86% identical, 32 lines differ
plugin/commands/debug.md · 73 lines

How it starts

The opening of the file, as written. The whole thing — 73 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/comfy-debug — Diagnose a Failed Workflow

The user wants to find out why a ComfyUI workflow execution failed and get a suggested fix.

Instructions

  1. Get the execution history. The argument is: $ARGUMENTS

    • If a prompt_id is provided, call get_history(action="list") with that prompt_id
    • If "last" is provided or no argument given, call get_history(action="list") with no prompt_id to get the most recent execution
  2. Extract the error. From the history response, identify:

    • node_id: the node where execution failed
    • node_type / class_type: what kind of node it was
    • exception_message: the error message
    • traceback: the full Python traceback

    If the execution succeeded (no error), tell the user it completed normally and show the output summary.

  3. Get relevant logs. Call get_system_stats (action:"logs") with a keyword filter matching the error. Use the exception class name (e.g., "RuntimeError", "ValueError") or a distinctive phrase from the error message. Request up to 200 lines.

  4. Inspect the failing node. Call create_workflow (action:"node_info") with the node_type of the failing node. Check:

    • What inputs does the node expect?
    • Are there required inputs that might be missing or mistyped?
    • What data types are expected for each input?
  5. Check for missing models. If the error mentions a missing file, model, or checkpoint:

    • Call list_local_models to see what's installed
    • Compare against what the workflow references
    • If a model is missing, suggest using download_model action:"download" or provide a search query for action:"search"
  6. Check for missing nodes. If the error is a KeyError or mentions an unknown node type:

    • The node pack may not be installed
    • Call search_custom_nodes (action: "search") with the node class name as query to find which pack provides it
    • Suggest installing the pack
  7. Present the diagnosis. Provide a summary:

    • What failed: node type, node ID, and a one-line description
    • Why it failed: root cause explanation in plain language
    • Suggested fix: concrete steps the user can take to resolve the issue
    • Traceback excerpt: the most relevant lines from the traceback (not the full dump)

Read the full file on GitHub · 73 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 73 lines · 9 tokens per session scan A 31f82a9175bd

Subscribe to this mod's changes

debug is a command published in the GitHub repository artokun/comfyui-mcp (701 stars, last pushed 2d ago), licensed MIT. It adds 9 tokens to every session and 920 once invoked, about $0.0000 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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