five

A root-cause analysis method that repeatedly asks why a problem happened, usually five times, to move from symptoms to the underlying cause.

In plain words
What is it for?
Use it to investigate bugs, crashes, process failures, and recurring issues, then plan preventive fixes and broader improvements.
Why use it?
It helps avoid fixing only the visible symptom and encourages checking whether the proposed cause is valid and would prevent the problem from returning.

Cursor rule

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.

agentmods
npx agentmods add rules/steipete/agent-rules/five
Clone the repo
git clone --depth 1 https://github.com/steipete/agent-rules
Per session 321 This file is loaded in full into every session.
When invoked 321 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
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 $0.00321 $0.00321
Opus 5 $0.00161 $0.00161
Sonnet 5 $0.00064 $0.00064
Haiku 4.5 $0.00032 $0.00032

Measured 2d ago against content hash c939af677fa1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

five 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 2d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

  • five — 100% identical, 0 lines differ
project-rules/five.mdc · 44 lines

What it actually says

Five Whys Analysis

Use the "Five Whys" root cause analysis technique to deeply understand problems.

Process:

1. Define the Problem

Clearly state the issue or symptom

2. Ask "Why?" Five Times

  • Why did this problem occur? → Answer 1
  • Why did Answer 1 happen? → Answer 2
  • Why did Answer 2 happen? → Answer 3
  • Why did Answer 3 happen? → Answer 4
  • Why did Answer 4 happen? → Answer 5 (Root Cause)

3. Validate Root Cause

  • Verify the logical chain
  • Check if addressing root cause prevents recurrence
  • Consider multiple root causes if applicable

4. Develop Solutions

  • Address the root cause, not just symptoms
  • Create preventive measures
  • Consider systemic improvements

Example:

Problem: Application crashes when processing large files

  1. Why? → The application runs out of memory
  2. Why? → It loads entire file into memory at once
  3. Why? → The file parser wasn't designed for streaming
  4. Why? → Initial requirements only specified small files
  5. Why? → Requirements gathering didn't consider future growth

Root Cause: Incomplete requirements gathering process Solution: Implement streaming parser and improve requirements process

Best Practices:

  • Focus on process, not people
  • Look for systemic issues
  • Document the analysis
  • Involve relevant stakeholders
  • Test solutions address root cause
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. 2d ago First seen · 44 lines · 321 tokens per session scan A c939af677fa1

Subscribe to this mod's changes

five is a cursor rule published in the GitHub repository steipete/agent-rules (5,696 stars, last pushed 4mo ago), licensed MIT. It adds 321 tokens to every session, about $0.0016 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.