five-whys-root-cause

five-whys-root-cause is a skill for Claude Code, Codex from fzfclee/consulting-skills. It costs 62 tokens per session (751 once invoked), scanned A, original, Apache-2.0.

A method for repeatedly asking why a recurring problem happened until reaching a cause that can be controlled. It can branch when the problem has more than one cause.

In plain words
What is it for?
Use it to investigate recurring incidents, failed fixes, and shallow explanations when there is a clear problem timeline and evidence.
Why use it?
It helps avoid fixing only visible symptoms or blaming people when the underlying process is responsible.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to investigate recurring incidents, failed fixes, and shallow explanations when there is a clear problem timeline and evidence.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/fzfclee/consulting-skills/five-whys-root-cause
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 fzfclee/consulting-skills --skill five-whys-root-cause
Clone the repo
git clone --depth 1 https://github.com/fzfclee/consulting-skills

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 five-whys-root-cause

README.md
[![agentmods](https://agentmods.dev/badge/skills/fzfclee/consulting-skills/five-whys-root-cause/github.svg)](https://agentmods.dev/skills/fzfclee/consulting-skills/five-whys-root-cause)
Your own site
<a href="https://agentmods.dev/skills/fzfclee/consulting-skills/five-whys-root-cause"><img src="https://agentmods.dev/badge/skills/fzfclee/consulting-skills/five-whys-root-cause/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 five-whys-root-cause

Your own site · 80×15
<a href="https://agentmods.dev/skills/fzfclee/consulting-skills/five-whys-root-cause"><img src="https://agentmods.dev/badge/skills/fzfclee/consulting-skills/five-whys-root-cause.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 62 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 751 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 $0.00062 $0.00751
Opus 5 $0.00031 $0.00376
Sonnet 5 $0.00012 $0.00150
Haiku 4.5 $0.00006 $0.00075

Measured 12d ago against content hash 5650c5eaa206, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

five-whys-root-cause 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 12d 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/five-whys-root-cause/SKILL.md · 88 lines

How it starts

The opening of the file, as written. The whole thing — 88 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Five Whys Root Cause

Use this skill to run Five Whys Root Cause as a practical consulting method, not as a generic framework explanation.

Method Notes

  • Ask why until reaching a controllable cause, not a person to blame.
  • Branch when the answer has multiple causes.

Required Inputs

Collect or infer these inputs before execution:

  • problem statement
  • evidence
  • timeline
  • constraints and failed fixes

If an input is missing, do not block automatically. Mark it as missing, state the assumption used, and add a validation action.

When Not To Use

Do not use when the problem has several interacting causal paths, feedback loops, or insufficient event evidence. A single Why chain can oversimplify a multi-causal system.

Adjacent Methods

  • fishbone-diagram: use when several cause branches must be compared.
  • systems-thinking: use when feedback, delay, or incentives keep recreating the issue.
  • constraint-analysis: use when one limiting factor is already visible.

Step-by-Step Execution

Step Required input How to execute Output
State problem Observed issue, impact, scope, time. Write one clear problem without blame. Problem statement.
Ask first why Problem and immediate evidence. Explain the direct cause with evidence. Cause 1.
Continue why chain Previous cause and evidence. Ask why again until reaching a controllable system/process cause. Cause chain.
Branch if needed Cause chain with multiple plausible causes. Split into parallel why chains when one answer hides multiple causes. Cause branches.
Convert to prevention Root cause and constraints. Define corrective action, owner, deadline, and recurrence check. Root-cause action plan.

Output Template

### 1. Problem Statement
Observed problem:
Expected state:
Evidence:
Boundary:

### 2. Why Chain
| Level | Why did this occur? | Evidence | Assumption |
|---|---|---|---|
|  |  |  |  |

### 3. Root Cause Judgment
Candidate root cause:
Mechanism:
Inside control:
Alternative branch:

### 4. Corrective And Preventive Action
| Action | Owner | Timing | Recurrence signal | Validation |
|---|---|---|---|---|
|  |  |  |  |  |

### Evidence And Next Decision
- Confirmed facts:
- Assumptions:
- Missing evidence:
- Next action, owner, and timing:
- Expected signal and decision threshold:

Read the full file on GitHub · 88 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. 12d ago First seen · 88 lines · 62 tokens per session scan A 5650c5eaa206

Subscribe to this mod's changes

five-whys-root-cause is a skill published in the GitHub repository fzfclee/consulting-skills (4 stars, last pushed 23d ago), licensed Apache-2.0. It adds 62 tokens to every session and 751 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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