debug

debug is a skill for Claude Code, Codex from angad-kandhari/deliberate. It costs 66 tokens per session (1,329 once invoked), scanned A, original, Apache-2.0.

A step-by-step method for finding and fixing software bugs, including bugs that cause tests to fail.

In plain words
What is it for?
It is for reproducing bugs, investigating failing tests, narrowing down causes, and fixing the underlying class of problem.
Why use it?
It helps separate what users see from the underlying cause, reducing guesswork and fixes that only hide the problem.

Skill for Claude CodeCodex

Part of the deliberate plugin — 13 skills, 1 hook shipped together

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/angad-kandhari/deliberate/debug
Any agent
npx skills add angad-kandhari/deliberate --skill debug
Clone the repo
git clone --depth 1 https://github.com/angad-kandhari/deliberate

Made for: Claude Code, Codex.

Or install deliberate, the plugin that ships this one along with the rest of its 13 skills, 1 hook.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for debug

README.md
[![agentmods](https://agentmods.dev/badge/skills/angad-kandhari/deliberate/debug.svg)](https://agentmods.dev/skills/angad-kandhari/deliberate/debug)
Your own site
<a href="https://agentmods.dev/skills/angad-kandhari/deliberate/debug"><img src="https://agentmods.dev/badge/skills/angad-kandhari/deliberate/debug.svg" alt="Measured on agentmods" height="20"></a>
Per session 66 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,329 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 $0.00066 $0.01329
Opus 5 $0.00033 $0.00665
Sonnet 5 $0.00013 $0.00266
Haiku 4.5 $0.00007 $0.00133

Measured 4d ago against content hash 441bc74b5664, 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 4d 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.

skills/debug/SKILL.md · 141 lines

How it starts

The opening of the file, as written. The whole thing — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debug

Debugging skill for LLM coding agents. Load this when the task is "fix the bug," "it's broken," "tests are failing," or any request that starts from a symptom rather than a feature.

Where deliberate keeps code honest, this skill keeps diagnosis honest. Counters the failure mode of trying random fixes until symptoms go away.


1. Reproduce Before You Reason

No repro, no fix.

  • Get the bug to happen on demand before touching code. A failing test is ideal; a manual repro with exact steps is the floor.
  • If you can't reproduce, that's the first bug to fix. Don't guess at root cause from a log snippet.
  • Write the repro down. It's the acceptance test for your fix.

If the user hands you a flaky or intermittent bug, say so:

"I can trigger this maybe 1 in 5 times. Before fixing, I want to find conditions that make it reliable - otherwise I can't tell if a fix worked."

Test: Can I make this bug happen whenever I want?


2. Symptom, Cause, Fix - Keep Them Separate

The symptom is not the bug.

State all three out loud before editing:

  • Symptom: what the user sees (error message, wrong output, crash).
  • Cause: why it happens (the actual defect in logic, state, or assumption).
  • Fix: the minimum change that addresses the cause.

If you can name the fix but not the cause, you're pattern-matching, not debugging. Stop.

Test: Could I explain to a new engineer why this bug existed, not just what I changed?


3. Bisect, Don't Guess

Narrow the search space systematically.

When the cause isn't obvious:

  • Git bisect when a behavior regressed. It's faster than reading diffs.
  • Binary search the code path: add a log or assertion halfway through, see which side the bug is on, repeat.
  • Minimize the repro until only the bug-relevant code remains.
  • Diff a working case against a broken case - the delta is the bug, almost always.

Random print statements across the codebase is not bisection. It's noise.

Read the full file on GitHub · 141 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. 4d ago First seen · 141 lines · 66 tokens per session scan A 441bc74b5664

Subscribe to this mod's changes

debug is a skill published in the GitHub repository angad-kandhari/deliberate (2 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 66 tokens to every session and 1,329 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 2026-08-31.

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