diagnose

diagnose is a skill for Codex from dayfinggg/openai-codex-agent-skills. It costs 54 tokens per session (516 once invoked), scanned A, original, MIT.

A structured investigation of a failure, regression, or slow operation that identifies its root cause using evidence.

In plain words
What is it for?
Use it to investigate crashes, broken behavior, flaky tests, regressions, or performance problems without changing the implementation.
Why use it?
It replaces guesses with a reproducible symptom, tested explanations, and a clear account of what caused the problem.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Good fit Use it to investigate crashes, broken behavior, flaky tests, regressions, or performance problems without changing the implementation.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/dayfinggg/openai-codex-agent-skills/diagnose
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 dayfinggg/openai-codex-agent-skills --skill diagnose
Clone the repo
git clone --depth 1 https://github.com/dayfinggg/openai-codex-agent-skills

Made for: 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 diagnose

README.md
[![agentmods](https://agentmods.dev/badge/skills/dayfinggg/openai-codex-agent-skills/diagnose/github.svg)](https://agentmods.dev/skills/dayfinggg/openai-codex-agent-skills/diagnose)
Your own site
<a href="https://agentmods.dev/skills/dayfinggg/openai-codex-agent-skills/diagnose"><img src="https://agentmods.dev/badge/skills/dayfinggg/openai-codex-agent-skills/diagnose/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 diagnose

Your own site · 80×15
<a href="https://agentmods.dev/skills/dayfinggg/openai-codex-agent-skills/diagnose"><img src="https://agentmods.dev/badge/skills/dayfinggg/openai-codex-agent-skills/diagnose.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 516 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 $0.00054 $0.00516
Opus 5 $0.00027 $0.00258
Sonnet 5 $0.00011 $0.00103
Haiku 4.5 $0.00005 $0.00052

Measured 5d ago against content hash a599b6efae05, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

diagnose 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 5d 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.

codex/skills/diagnose/SKILL.md · 39 lines

How it starts

The opening of the file, as written. The whole thing — 39 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Diagnose

Follow the governing instructions and the user's requirements for communication, code style, authorization, and delegation. This skill supplies task-specific guidance, not permission to expand the task. Its workflow and output fields describe internal checks and relevant content, not a mandatory response layout or a progress report. When used within broader authorized work, continue that work through completion rather than stopping to deliver this skill's intermediate result.

Replace speculation with a short feedback loop and a causal explanation.

Reproduce

Capture the exact symptom, environment, inputs, expected behavior, and observed behavior. Find the smallest reliable reproduction. If the failure is intermittent, identify the condition that changes its probability instead of adding arbitrary waits.

Preserve a working baseline or last-known-good observation before changing the experiment so later comparisons remain meaningful.

Narrow

Follow the failing value or event backward through boundaries. Compare a working and failing path when possible. Test one hypothesis at a time with the cheapest discriminating observation. Read logs and code around the first incorrect state, not only the final exception.

For ordering or concurrency failures, build a timestamped event trace with identities and state transitions, then reproduce the smallest relevant interleaving with coordination primitives rather than sleep-based timing.

Establish cause

A root cause must explain the symptom, the triggering conditions, and why the system did not prevent it. Verify the explanation by changing or isolating the causal condition without silently shipping a fix.

After establishing the cause, search the affected scope for analogous code, data, configuration, or tests that share the same faulty assumption. Report the likely family separately from the proven reproduction.

Boundaries

Do not implement a repair for a diagnosis-only request. Do not hide the symptom with retries, guards, or broader timeouts. Redact secrets and personal data from evidence.

Read the full file on GitHub · 39 lines

Files

What ships with it

1 file 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. 5d ago Changed · +2 lines a599b6efae05
  2. 7d ago Changed · +8 lines 04ec1003b6d5
  3. 12d ago First seen · 29 lines · 54 tokens per session scan A 24eaa61d1a79

Subscribe to this mod's changes

diagnose is a skill published in the GitHub repository dayfinggg/openai-codex-agent-skills (4 stars, last pushed 3d ago), licensed MIT. It adds 54 tokens to every session and 516 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.

Related

Other skills, from other repositories

bug-detective

This skill should be used when the user asks to "debug this", "fix this error", "investigate this bug", "troubleshoot this issue", "find the problem", "something is broken", "this isn't working", "why is this failing", or reports errors/exceptions/bugs. Provides systematic debugging workflow and common error patterns.

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tldr

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fix

Debug and fix bugs/errors/failures, including merge conflicts and failing PR CI checks. Triggers "fix", "broken", "not working", "bug", "error", "failing", "merge conflict", "fix CI", "checks failing", console errors, build/test failures, regression.

darkroomengineering/cc-settings · 63 tokens

explore

Read-only codebase investigation via Explore agent; also handles upward-zoom for unfamiliar code regions. Triggers "how does X work", "where is X", "find X", "understand X", "navigate codebase", "zoom out", "bigger picture", "where does this fit".

darkroomengineering/cc-settings · 64 tokens

refactor

Behavior-preserving restructuring of code NOT in your current diff — extract modules, rename across files, pay down tech debt. For just-changed code use /zero-tech-debt. Triggers "refactor X", "restructure", "extract Y from Z".

darkroomengineering/cc-settings · 56 tokens

triage

First-pass review of a client or unfamiliar repo — sweep for glaring issues, report ranked findings. READ-ONLY on external repos. Triggers "triage this repo", "point out glaring issues", "first pass on this client repo".

darkroomengineering/cc-settings · 51 tokens