debug-investigator

debug-investigator is a skill for Claude Code from Mathews-Tom/armory. It costs 64 tokens per session (3,193 once invoked), scanned A, original, MIT.

A structured method for investigating difficult software bugs by forming and ranking possible causes, gathering evidence, and testing each explanation.

In plain words
What is it for?
Use it to analyze logs and stack traces, plan instrumentation, choose a git bisect strategy, and create a small reproduction of the problem.
Why use it?
It replaces trial-and-error debugging with a documented process for intermittent failures, performance regressions, and bugs without an obvious error trace.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the armory plugin — 85 skills shipped together

Good fit Use it to analyze logs and stack traces, plan instrumentation, choose a git bisect strategy, and create a small reproduction of the problem.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mathews-tom/armory/debug-investigator
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 Mathews-Tom/armory --skill debug-investigator
Clone the repo
git clone --depth 1 https://github.com/Mathews-Tom/armory

Made for: Claude Code.

Or install armory, the plugin that ships this one along with the rest of its 85 skills.

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-investigator

README.md
[![agentmods](https://agentmods.dev/badge/skills/mathews-tom/armory/debug-investigator.svg)](https://agentmods.dev/skills/mathews-tom/armory/debug-investigator)
Your own site
<a href="https://agentmods.dev/skills/mathews-tom/armory/debug-investigator"><img src="https://agentmods.dev/badge/skills/mathews-tom/armory/debug-investigator.svg" alt="Measured on agentmods" height="20"></a>
Per session 64 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,193 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00064 $0.03193
Opus 5 $0.00032 $0.01597
Sonnet 5 $0.00013 $0.00639
Haiku 4.5 $0.00006 $0.00319

Measured 7d ago against content hash 85f90b165b84, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

debug-investigator 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 7d 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-investigator/SKILL.md · 306 lines

How it starts

The opening of the file, as written. The whole thing — 306 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debug Investigator

Structured debugging methodology that replaces ad-hoc exploration with hypothesis-driven investigation. Captures symptoms, builds a deterministic feedback loop, analyzes evidence (stacktraces, logs, state), generates ranked hypotheses, designs bisection strategies, identifies instrumentation points, and produces minimal reproductions — documenting every step so dead ends are never revisited.

When to use this skill vs native debugging: The base model handles straightforward debugging (clear stacktraces, obvious errors) natively. Use this skill for non-obvious bugs requiring systematic investigation: intermittent failures, bugs with no clear stacktrace, performance regressions, or issues requiring git bisection and hypothesis ranking.

Reference Files

File Contents Load When
references/stacktrace-patterns.md Exception taxonomy, traceback reading, common Python/JS error signatures Stacktrace or exception present
references/hypothesis-templates.md Bug category catalog, probability ranking, confirmation/refutation tests Always
references/bisection-guide.md git bisect workflow, binary search debugging, narrowing techniques Bug appeared after a change
references/log-analysis.md Log pattern extraction, anomaly detection, timeline correlation Log output available
references/instrumentation-points.md Strategic logging placement, breakpoint strategy, state inspection techniques Investigation plan needed

Prerequisites

  • git — for bisection and history analysis
  • Access to source code — cannot debug opaque binaries
  • Reproducible environment — or at minimum, error output (stacktrace, logs)

Read the full file on GitHub · 306 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 7d ago First seen · 306 lines · 64 tokens per session scan A 85f90b165b84

Subscribe to this mod's changes

debug-investigator is a skill published in the GitHub repository Mathews-Tom/armory (316 stars, last pushed yesterday), licensed MIT. It adds 64 tokens to every session and 3,193 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.

Related

Other skills, from other repositories

qa-to-engineering-brief

Converts bug reports, screenshots, user panic, QA notes, and vague complaints into durable engineering briefs. Use when turning observed failures into reproducible issues with severity, expected behaviour, evidence, scope, owner, and acceptance tests.

joelbrilliant/agentic-delivery-skills · 53 tokens

review-with-dora

Use when reviewing agent context (SKILL.md, plugin, rule, AGENTS.md) with dora before reporting done. Also when ask-dora routes a Dora job (review, fix, unused, scan), or the user asks to review, diagnose, or clean up Claude, Cursor, Codex, Copilot, or Grok context.

saif-shines/doraval · 75 tokens

comet-hotfix

A quick workflow for fixing an existing bug in Comet, a tool that manages structured code changes. It moves through opening the change, building, checking, and archiving it.

rpamis/comet · 29 tokens

comet-hotfix

Comet preset path: Bug fix / hotfix. Skip brainstorming, directly open → build → verify → archive. Applicable for behavior fixes, scenarios not involving new capability design.

rpamis/comet · 40 tokens

comet-github-issue-triage

A read-only workflow for checking and classifying Comet GitHub Issues, which are reports or requests about a software project. It compares each report with the repository’s code, tests, configuration, installation behavior, and existing issues.

rpamis/comet · 66 tokens

cherry-electron-dev

Develop, fix, and profile Cherry Studio in a tracked Electron instance. Use for everyday implementation, UI and interaction work, bug fixing, runtime debugging, DevTools inspection, lag or jank investigation, CPU and memory monitoring, leak checks, and startup-performance analysis; reuse a verified workspace instance…

CherryHQ/cherry-studio · 75 tokens