debug

A structured procedure for investigating a software problem by reproducing it, narrowing down where it occurs, and identifying its cause. It is intended for errors, unexpected behavior, and differences between environments such as staging and production.

In plain words
What is it for?
Use it when you have an error message, stack trace, deployment regression, or behavior that differs from expectations. It guides the work from reproduction through isolation and diagnosis.
Why use it?
Unstructured debugging can lead to guesses and unrelated changes. This process keeps the investigation tied to the expected behavior, reproduction steps, logs, recent changes, and the affected code path.

Skill for Claude CodeCodex

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 skills/anthropics/knowledge-work-plugins/debug
Any agent
npx skills add anthropics/knowledge-work-plugins --skill debug
Clone the repo
git clone --depth 1 https://github.com/anthropics/knowledge-work-plugins

Made for: Claude Code, Codex.

Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 700 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 $0.00053 $0.00700
Opus 5 $0.00026 $0.00350
Sonnet 5 $0.00011 $0.00140
Haiku 4.5 $0.00005 $0.00070

Measured 2d ago against content hash e50bb92cbcb2, 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

3 near-identical copies found in the catalogue:

  • debug — 100% identical, 0 lines differ
  • debug — 100% identical, 0 lines differ
  • debug-th — 91% identical, 4 lines differ
engineering/skills/debug/SKILL.md · 96 lines

How it starts

The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/debug

If you see unfamiliar placeholders or need to check which tools are connected, see CONNECTORS.md.

Run a structured debugging session to find and fix issues systematically.

Usage

/debug $ARGUMENTS

How It Works

┌─────────────────────────────────────────────────────────────────┐
│                       DEBUG                                        │
├─────────────────────────────────────────────────────────────────┤
│  Step 1: REPRODUCE                                                │
│  ✓ Understand the expected vs. actual behavior                   │
│  ✓ Identify exact reproduction steps                             │
│  ✓ Determine scope (when did it start? who is affected?)        │
│                                                                    │
│  Step 2: ISOLATE                                                   │
│  ✓ Narrow down the component, service, or code path             │
│  ✓ Check recent changes (deploys, config changes, dependencies) │
│  ✓ Review logs and error messages                                │
│                                                                    │
│  Step 3: DIAGNOSE                                                  │
│  ✓ Form hypotheses and test them                                 │
│  ✓ Trace the code path                                           │
│  ✓ Identify root cause (not just symptoms)                      │
│                                                                    │
│  Step 4: FIX                                                       │
│  ✓ Propose a fix with explanation                                │
│  ✓ Consider side effects and edge cases                          │
│  ✓ Suggest tests to prevent regression                           │
└─────────────────────────────────────────────────────────────────┘

What I Need From You

Tell me about the problem. Any of these help:

  • Error message or stack trace
  • Steps to reproduce
  • What changed recently
  • Logs or screenshots
  • Expected vs. actual behavior

Read the full file on GitHub · 96 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 · 96 lines · 53 tokens per session scan A e50bb92cbcb2

Subscribe to this mod's changes

debug is a skill published in the GitHub repository anthropics/knowledge-work-plugins (23,791 stars, last pushed today), licensed Apache-2.0. It adds 53 tokens to every session and 700 once invoked, about $0.0003 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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