5whys

Five Whys root cause analysis. Iteratively asks "why" to drill past symptoms to underlying causes. Use for debugging, investigating failures, or understanding why something went wrong.

181 stars

Best use case

5whys is best used when you need a repeatable AI agent workflow instead of a one-off prompt.

Five Whys root cause analysis. Iteratively asks "why" to drill past symptoms to underlying causes. Use for debugging, investigating failures, or understanding why something went wrong.

Teams using 5whys should expect a more consistent output, faster repeated execution, less prompt rewriting.

When to use this skill

  • You want a reusable workflow that can be run more than once with consistent structure.

When not to use this skill

  • You only need a quick one-off answer and do not need a reusable workflow.
  • You cannot install or maintain the underlying files, dependencies, or repository context.

Installation

Claude Code / Cursor / Codex

$curl -o ~/.claude/skills/5whys/SKILL.md --create-dirs "https://raw.githubusercontent.com/majiayu000/claude-skill-registry/main/skills/data/5whys/SKILL.md"

Manual Installation

  1. Download SKILL.md from GitHub
  2. Place it in .claude/skills/5whys/SKILL.md inside your project
  3. Restart your AI agent — it will auto-discover the skill

How 5whys Compares

Feature / Agent5whysStandard Approach
Platform SupportNot specifiedLimited / Varies
Context Awareness High Baseline
Installation ComplexityUnknownN/A

Frequently Asked Questions

What does this skill do?

Five Whys root cause analysis. Iteratively asks "why" to drill past symptoms to underlying causes. Use for debugging, investigating failures, or understanding why something went wrong.

Where can I find the source code?

You can find the source code on GitHub using the link provided at the top of the page.

SKILL.md Source

# Five Whys Analysis

Perform iterative root cause analysis by asking "why" repeatedly until you reach the underlying cause.

## Instructions

Start with the stated problem and ask "why" it occurred. For each answer, ask "why" again. Continue until you reach a root cause that:
- Is actionable (you can do something about it)
- Is fundamental (asking "why" further leads to abstract/unhelpful answers)
- Explains the chain of causation

Typically this takes 5 iterations, but may be fewer or more.

### Output Format

**Problem Statement**
Restate the problem clearly and specifically.

**Why Chain**

| Level | Question | Answer |
|-------|----------|--------|
| 1 | Why did [problem]? | [Answer 1] |
| 2 | Why did [Answer 1]? | [Answer 2] |
| 3 | Why did [Answer 2]? | [Answer 3] |
| 4 | Why did [Answer 3]? | [Answer 4] |
| 5 | Why did [Answer 4]? | [Root Cause] |

**Root Cause**
The fundamental issue identified. Explain why this is the root (not just another symptom).

**Branches** (if applicable)
If multiple valid answers exist at any level, show the branching analysis.

**Corrective Actions**
- Immediate: What to do now to address the symptom
- Systemic: What to change to prevent recurrence

**Verification**
How will you confirm the root cause is correct? (Test the hypothesis)

## Guidelines

- Each answer should be factual and verifiable
- Avoid blame ("John didn't do X")—focus on systems and processes
- If you're guessing, note it as a hypothesis to verify
- Watch for circular logic
- It's okay to branch if there are multiple valid causes
- Stop when further "why" questions become philosophical or unhelpful

## Examples

### Software Bug

**Problem**: Users are seeing 500 errors on the checkout page

| Level | Question | Answer |
|-------|----------|--------|
| 1 | Why are users seeing 500 errors? | The payment service is timing out |
| 2 | Why is the payment service timing out? | Database queries are taking >30 seconds |
| 3 | Why are database queries slow? | The orders table has 50M rows and no index on customer_id |
| 4 | Why is there no index? | The table was created before we had this query pattern |
| 5 | Why wasn't an index added when the query was added? | No database review process for new queries |

**Root Cause**: Missing process for database review when adding new query patterns.

**Corrective Actions**:
- Immediate: Add index on customer_id
- Systemic: Add database review checklist to PR template

### Customer Churn

**Problem**: Enterprise customer canceled after 6 months

| Level | Question | Answer |
|-------|----------|--------|
| 1 | Why did the customer cancel? | They said the product wasn't delivering value |
| 2 | Why wasn't it delivering value? | They only had 12% feature adoption |
| 3 | Why was adoption so low? | Users weren't trained on key workflows |
| 4 | Why weren't users trained? | Onboarding ended after technical setup |
| 5 | Why does onboarding end at setup? | Success team is understaffed; prioritizes new sales |

**Root Cause**: Success team capacity forces them to end onboarding prematurely.

**Corrective Actions**:
- Immediate: Reach out to at-risk accounts with training
- Systemic: Hire success capacity; redefine onboarding to include adoption milestone

$ARGUMENTS

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