root-cause

root-cause is a skill for Claude Code from larsboes/Axon. It costs 166 tokens per session (1,417 once invoked), scanned A, original, MIT.

An investigation workflow for finding why a failure that already happened occurred. It builds a timeline, tests possible causes against evidence, and ends with a cause, a way to disprove it, and ranked fixes.

In plain words
What is it for?
Use it for incidents, broken automations, regressions, or other failures when you need a timeline, a falsifiable explanation, and fixes that address the wider problem.
Why use it?
It separates observed facts from early guesses and focuses on system conditions rather than blaming the last person who made a change.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the deliberation plugin — 4 skills, 7 agents shipped together

Good fit Use it for incidents, broken automations, regressions, or other failures when you need a timeline, a falsifiable explanation, and fixes that address the wider problem.

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

Made for: Claude Code.

Or install deliberation, the plugin that ships this one along with the rest of its 4 skills, 7 agents.

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 root-cause

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/larsboes/axon/root-cause"><img src="https://agentmods.dev/badge/skills/larsboes/axon/root-cause.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 166 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,417 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 $0.00166 $0.01417
Opus 5 $0.00083 $0.00709
Sonnet 5 $0.00033 $0.00283
Haiku 4.5 $0.00017 $0.00142

Measured 9d ago against content hash 9c8b9808a9ee, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-15, from the pricing page.

Security

Grade A, and why

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 9d 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.

Packs/deliberation/skills/root-cause/SKILL.md · 106 lines

How it starts

The opening of the file, as written. The whole thing — 106 lines — stays where its author put it; the contents beside it link to each section on GitHub.

root-cause

One failure goes in. A named cause, the probe that would falsify it, and a fix ranked by whether it removes the class come out.

Root-cause explains a failure that already happened. To attack a proposal before it ships, use red-team. To choose between two repairs, use council.

Adapted from the RootCauseAnalysis skill in LifeOS by Daniel Miessler (https://github.com/danielmiessler/LifeOS), MIT.

Procedure

Copy this checklist and track progress:

- [ ] 1. State the failure as an observation, not a diagnosis
- [ ] 2. Build the timeline
- [ ] 3. List what changed
- [ ] 4. Pick the method
- [ ] 5. Generate candidate causes, then try to refute each one
- [ ] 6. Name the cause and its falsifying probe
- [ ] 7. Rank the fixes by what class each one removes

1 — State the failure. Write what was observed, when it started, and how it was noticed. "The automations stopped running" is an observation. "The restart wiped them" is a diagnosis, and writing one here decides the investigation before it starts. Say which of the two you were handed.

2 — Build the timeline. Read the logs, the history, the git log, the state file — whatever records time. Put every dated fact in order, including the boring ones. Mark the last moment the system is known to have worked and the first moment it is known to have failed. The cause is between those two marks, and most investigations that fail never drew them.

3 — List what changed. In that window: deploys, config edits, upgrades, credentials, network, hardware, and anything a person or an agent ran by hand. A failure with no change behind it is possible but rare; when the list is empty, say so explicitly, because it moves the answer toward a latent condition that was always there and toward what made it visible today.

4 — Pick the method. Read references/methods.md and pick the one the evidence supports:

The evidence you have Method
A clean timeline and a suspect change Change analysis
One failure, a chain of mechanism to walk back Five whys
It fails here and not there, now and not then Is / is-not
Several possible paths to the same symptom Fault tree
It already failed more than once Recurrence pattern
An incident that is over and needs a record Blameless postmortem

Read the full file on GitHub · 106 lines

Files

What ships with it

2 files 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. 9d ago First seen · 106 lines · 166 tokens per session scan A 9c8b9808a9ee

Subscribe to this mod's changes

root-cause is a skill published in the GitHub repository larsboes/Axon (1 stars, last pushed yesterday), licensed MIT. It adds 166 tokens to every session and 1,417 once invoked, about $0.0008 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 2026-09-07.