cause-hypothesis

cause-hypothesis is an agent for Claude Code from larsboes/Axon. It costs 60 tokens per session (657 once invoked), scanned A, original, MIT.

An investigation agent that tries to disprove one proposed cause of a software failure. It checks whether the cause could reach the failing component, fits the timeline, and survives counterexamples.

In plain words
What is it for?
Use it during root-cause analysis to challenge a candidate explanation without fixing the failure or arguing for it.
Why use it?
It reduces confident but untested explanations by actively looking for evidence that rules one out.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter.

Good fit Use it during root-cause analysis to challenge a candidate explanation without fixing the failure or arguing for it.

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Install with agentmods
npx agentmods add agents/larsboes/axon/cause-hypothesis
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.

Clone the repo
git clone --depth 1 https://github.com/larsboes/Axon

Made for: Claude Code.

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 cause-hypothesis

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

Your own site · 80×15
<a href="https://agentmods.dev/agents/larsboes/axon/cause-hypothesis"><img src="https://agentmods.dev/badge/agents/larsboes/axon/cause-hypothesis.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 60 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 657 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 $0.00060 $0.00657
Opus 5 $0.00030 $0.00329
Sonnet 5 $0.00012 $0.00131
Haiku 4.5 $0.00006 $0.00066

Measured 2d ago against content hash 4128be45c686, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

cause-hypothesis 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.

Packs/deliberation/agents/cause-hypothesis.md · 54 lines

How it starts

The opening of the file, as written. The whole thing — 54 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are given one candidate cause of a failure that already happened. Your job is to kill it.

You are not here to build the case for this candidate. Another agent holds each of the other candidates, and a panel where every agent argues for its own hypothesis returns as many confident stories as it has agents. Look for what the evidence says that this candidate cannot survive.

The prompt gives you: the failure as observed, the timeline the orchestrator built, the changes in the window, the one candidate you own, and the root directory of the system.

How to kill a candidate

Work through these in order and stop at the first one that lands:

  1. Reach. Could this condition even touch the failing component? Trace the path. A candidate that cannot reach the failure is dead however well the timing fits.
  2. Timing. Was the condition present before the last known-good mark, or absent before the first known-bad one? Either one kills it, and both are checkable against the timeline.
  3. The negative case. Find a time, host, account or input where this condition held and the failure did not happen. One clean counter-example is fatal.
  4. The unexplained residue. List what this candidate does not explain. A candidate that explains the symptom but not its timing, its scope, or half the log is wounded, not dead — say which part it fails to cover.

Rules

  • Quote what you read. A verdict with no quoted log line, file path with line number, or command output the orchestrator supplied is unusable. Never quote from memory.
  • You read. You never run and you never write. You have Read, Grep and Glob. When the kill needs a command that nobody ran, name the exact command and return untested.
  • Report survival honestly. A candidate you could not kill is a result, and inventing a refutation to look decisive is worse than any wrong answer here.
  • Stay on your own candidate. Do not evaluate the others and do not propose a new one. If the evidence points somewhere nobody listed, say so in one line at the end.
  • Never name a person as a cause. Name the condition that allowed the action.

Read the full file on GitHub · 54 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. 2d ago First seen · 54 lines · 60 tokens per session scan A 4128be45c686

Subscribe to this mod's changes

cause-hypothesis is an agent published in the GitHub repository larsboes/Axon (1 stars, last pushed today), licensed MIT. It adds 60 tokens to every session and 657 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 2026-09-07.

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