nobrainer-rca

nobrainer-rca is a skill for Claude Code from nobrainer-tech/nobrainer-tech-skills. It costs 55 tokens per session (1,301 once invoked), scanned A, original, MIT.

A root-cause-analysis skill for explaining why a specific incident, regression, test failure, outage, wrong value, or unexpected behavior happened.

In plain words
What is it for?
It helps frame incidents, reproduce failures, test hypotheses, reconcile evidence, and produce a durable diagnosis for one specific problem.
Why use it?
It keeps investigation focused on evidence and requires diagnosis before suggesting or making a fix. Root-cause analysis means tracing an observed problem back to its underlying cause.

Skill for Claude Code

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

Part of the nobrainer-tech-skills plugin — 15 skills shipped together

Good fit It helps frame incidents, reproduce failures, test hypotheses, reconcile evidence, and produce a durable diagnosis for one specific problem.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/nobrainer-tech/nobrainer-tech-skills/nobrainer-rca
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 nobrainer-tech/nobrainer-tech-skills --skill nobrainer-rca
Clone the repo
git clone --depth 1 https://github.com/nobrainer-tech/nobrainer-tech-skills

Made for: Claude Code.

Or install nobrainer-tech-skills, the plugin that ships this one along with the rest of its 15 skills.

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 nobrainer-rca

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/nobrainer-tech/nobrainer-tech-skills/nobrainer-rca"><img src="https://agentmods.dev/badge/skills/nobrainer-tech/nobrainer-tech-skills/nobrainer-rca.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,301 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 $0.00055 $0.01301
Opus 5 $0.00028 $0.00651
Sonnet 5 $0.00011 $0.00260
Haiku 4.5 $0.00006 $0.00130

Measured 11d ago against content hash 604d0bb88dba, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

nobrainer-rca 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 11d 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/nobrainer-rca/SKILL.md · 163 lines

How it starts

The opening of the file, as written. The whole thing — 163 lines — stays where its author put it; the contents beside it link to each section on GitHub.

NoBrainer Root Cause Analysis

Explain a specific observed failure with a continuous evidence chain. Diagnose before proposing or implementing a fix. Use the project's maintained debugging and tracing capabilities for reproduction and hypothesis tests; this skill owns incident framing, adaptive independent investigation, evidence reconciliation and a durable RCA verdict.

Do not use for broad code auditing, risk review, or choosing among already-known solutions. Those are different tasks.

Investigation contract

Freeze the incident before searching:

SYMPTOM: <literal observation>
EXPECTED: <contract or baseline>
WHEN: <timestamp/window/version>
ENVIRONMENT: <runtime, release, region/account boundary>
REPRODUCTION: REPRODUCIBLE | INTERMITTENT | NOT_REPRODUCED
IMPACT: <users/data/money/availability>
LAST_KNOWN_GOOD: <version/time or UNKNOWN>
FROZEN_INPUTS: <logs, commit, config snapshot, request IDs or UNKNOWN>
WRITE_AUTHORITY: READ_ONLY unless explicitly expanded

Ask one focused clarification only when a missing value changes where or how to investigate. Otherwise mark it UNKNOWN and gather evidence. Never put secrets or full sensitive payloads in prompts or reports.

Calibrate investigation breadth

Default to one primary investigator. Add independent perspectives only when the system boundary or evidence warrants them:

  • LIGHT: one deterministic local failure with a short trace and one subsystem.
  • STANDARD: three to five bounded perspectives for multiple layers, timing, state, configuration or external dependencies.
  • HIGH: five to eight perspectives for production incidents, data/money, intermittent concurrency, security boundaries, or conflicting evidence.

Possible perspectives are forward trace, backward data lineage, timeline/logs, configuration/state, dependency boundary, cache/concurrency/timing, hypothesis killer, and similar-incident history. Assign only relevant ones. Ten generic agents are not rigor; coverage of real uncertainty is rigor.

Read the full file on GitHub · 163 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. 11d ago First seen · 163 lines · 55 tokens per session scan A 604d0bb88dba

Subscribe to this mod's changes

nobrainer-rca is a skill published in the GitHub repository nobrainer-tech/nobrainer-tech-skills (5 stars, last pushed 6d ago), licensed MIT. It adds 55 tokens to every session and 1,301 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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