Diagnose and Fix Bugs Agent Skill

Use when diagnosing or fixing functional bugs, flaky tests, regressions, crashes, data corruption symptoms, production incidents, or…

Context cost
2.2k tokensestimated from the bundle, loaded when it triggers
Bundle
5 files · 9.6 kB1 script among them — read before you run
Licence
not declarednone named by its author
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Use when diagnosing or fixing functional bugs, flaky tests, regressions, crashes, data corruption symptoms, production incidents, or unexplained incorrect behavior. Builds a tight feedback loop, reproduces and minimizes the failure, tests falsifiable hypotheses, isolates root cause, applies a minimal fix, adds regression coverage, cleans up instrumentation, and reports remaining uncertainty. Use performance-engineering instead when latency, throughput, memory, CPU, IO, or contention is the dominant symptom.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

securitytesting

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md4.3 kB · preview
--- name: diagnose-and-fix-bugs ---
6# Diagnose and Fix Bugs
7
8## Core Contract
9
10- Start with the narrowest reliable pass/fail signal that exercises the reported symptom.
11- Before proposing a code-level cause, locate the relevant implementation in the exact version that ran and trace the entry point, call path, state or data changes, and effective configuration that can produce the symptom. Use logs and metrics to test that code mechanism, not replace source inspection.
12- Scale rigor to difficulty: one strong hypothesis may be enough for an obvious bug; hard bugs need a tighter loop, minimization, and ranked hypotheses.
13- Do not make a speculative fix when the failure cannot be reproduced or supported by evidence.
14- Fix root cause with the smallest safe change and leave regression coverage or a clear reproduction note.
15
16## Workflow
17
181. State observed and expected behavior.
192. Build a feedback loop: a test, CLI command, request script, browser check, trace replay, harness, differential run, or human-guided script that can catch this exact failure.
203. Reproduce the issue and minimize the scenario. For flaky bugs, raise and measure the reproduction rate rather than waiting for a perfect repro.
214. Locate the relevant code in the exact executed version. Trace from the runtime entry point through callers, callees, state or data transformations, and effective configuration to the observed behavior.
225. Map logs, metrics, traces, inputs, tests, environment, versions, and recent changes to that code path.
236. Form falsifiable hypotheses. For hard bugs, rank 3–5 and state what observation would confirm or reject each one.
247. Test one variable at a time. Prefer debugger inspection or targeted, uniquely tagged logs; do not log everything.
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md623 words
Files5
Licencenot declared
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈140
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
2,060
on trigger
The instruction body and 4 supporting files, read only when the skill fires.
1.1%
of a 200k window
Ten skills this size would take about 11% of the window before you open a file.
050k100k150k200k context window

2.2k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Middling. Fine to keep on in a project where you use it weekly, worth unloading in one where you never do.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

5 files, 9.6 kB on disk. Mostly text — the instructions the model reads — with 1 script in it that your client would run only if the instructions tell it to.

  • SKILL.md4.3 kB
  • agents/openai.yaml0.3 kB
  • references/debugging-playbook.md3.1 kB
  • references/regression-test-checklist.md1.1 kB
  • scripts/hitl-loop.template.sh0.8 kB
What is not in it

A skill installs nothing and depends on nothing: it is a folder your client reads. This one carries 1 script beside the text, so the bundle is 5 files you can review in full before installing.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Diagnose and Fix Bugs · 2.2k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/diagnose-and-fix-bugs/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/diagnose-and-fix-bugs" ] && { [ ! -e .claude/skills/diagnose-and-fix-bugs ] || { mv .claude/skills/diagnose-and-fix-bugs "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/diagnose-and-fix-bugs" .claude/skills/ && echo "Installed .claude/skills/diagnose-and-fix-bugs"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add 3aceshowhand/diagnose-and-fix-bugs

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/diagnose-and-fix-bugs/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/diagnose-and-fix-bugs/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/diagnose-and-fix-bugs" ] && { [ ! -e ~/.claude/skills/diagnose-and-fix-bugs ] || { mv ~/.claude/skills/diagnose-and-fix-bugs "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/diagnose-and-fix-bugs" ~/.claude/skills/ && echo "Installed ~/.claude/skills/diagnose-and-fix-bugs" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/diagnose-and-fix-bugs/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Versionnot versioned
Publishedno release date on file
PriceFree
Reference3aceshowhand/diagnose-and-fix-bugs

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

Reviews

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