debugger

debugger is a skill for Claude Code, Codex from johnefemer/skillfish. It costs 0 tokens per session (11,249 once invoked), scanned C, original, no licence file.

A structured guide to finding the causes of software problems. It covers debugger setup, logging, memory leaks, and race conditions, where timing makes bugs difficult to reproduce.

In plain words
What is it for?
Use it to investigate failures in code, configure VS Code or Chrome DevTools, improve logs, and diagnose leaks or timing-related errors.
Why use it?
It helps replace guesswork with a repeatable process for locating and explaining bugs.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it to investigate failures in code, configure VS Code or Chrome DevTools, improve logs, and diagnose leaks or timing-related errors.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/johnefemer/skillfish/debugger
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.

Any agent
npx skills add johnefemer/skillfish --skill debugger
Clone the repo
git clone --depth 1 https://github.com/johnefemer/skillfish

Made for: Claude Code, Codex.

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 debugger

README.md
[![agentmods](https://agentmods.dev/badge/skills/johnefemer/skillfish/debugger/github.svg)](https://agentmods.dev/skills/johnefemer/skillfish/debugger)
Your own site
<a href="https://agentmods.dev/skills/johnefemer/skillfish/debugger"><img src="https://agentmods.dev/badge/skills/johnefemer/skillfish/debugger/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for debugger

Your own site · 80×15
<a href="https://agentmods.dev/skills/johnefemer/skillfish/debugger"><img src="https://agentmods.dev/badge/skills/johnefemer/skillfish/debugger.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 11,249 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 3 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 5.1 $0.00000 $0.11249
Opus 5.5 $0.00000 $0.04500
Sonnet 5.5 $0.00000 $0.02250
Haiku 4.5 $0.00000 $0.01125

Measured 2mo ago against content hash f431bb6281df, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade C, and why

debugger scanned grade C with 3 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 2mo 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.

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

# Test: curl -X POST -H "Content-Type: application/json" -d '{"big":"data..."}' localhost:3000/data

Asks for rootmediumPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

echo '/tmp/core.%e.%p' | sudo tee /proc/sys/kernel/core_pattern

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

# Test: curl -X POST -H "Content-Type: application/json" -d '{"big":"data..."}' localhost:3000/data
skills/debugger/SKILL.md · 1,491 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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. 2mo ago First seen · 1,491 lines · 0 tokens per session scan C f431bb6281df

Subscribe to this mod's changes

debugger is a skill published in the GitHub repository johnefemer/skillfish (4 stars, last pushed 4d ago), with no licence file. It costs nothing until one of its globs matches a file; then it loads 11,249 tokens. A static security scan graded it C with 3 findings (sends data to an external url, asks for root, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

Related

debugger compared with skills from other repositories

debugger next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
debuggerjohnefemer/skillfishSkill44d agononeC0Claude Code, Codex
systematic-debuggingopen-metadata/OpenMetadataSkill16kyesterdayApache-2.0A37Claude Code
log-error-digestzebbern/claude-code-guideSkill4.7k3d agoMITA71Claude Code, Codex
cwv-optimizeradobe/skillsSkill319yesterdayApache-2.0A112Claude Code
ci-fixersipyourdrink-ltd/bernsteinSkill1.2kyesterdayApache-2.0A15Claude Code, Codex
triaging-web-analytics-supportPostHog/posthogSkill41kyesterdaynoneA151Claude Code, Codex
diagnosing-missing-recordingsPostHog/posthogSkill41kyesterdaynoneA76Claude Code, Codex