error-analysis

error-analysis is a skill for Claude Code from hamelsmu/evals-skills. It costs 53 tokens per session (1,745 once invoked), scanned A, original, MIT.

A guide for studying how an AI or large language model pipeline fails by examining its recorded traces, which show the inputs, intermediate steps, and final answers.

In plain words
What is it for?
Use it to review representative traces, label successes and failures, group recurring problems, and measure failure rates after incidents or major changes.
Why use it?
It turns scattered failures into named categories and rates, making it clearer which problems should be fixed first.

Skill for Claude Code

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

Part of the evals-skills plugin — 7 skills shipped together

Good fit Use it to review representative traces, label successes and failures, group recurring problems, and measure failure rates after incidents or major changes.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/hamelsmu/evals-skills/error-analysis
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 hamelsmu/evals-skills --skill error-analysis
Clone the repo
git clone --depth 1 https://github.com/hamelsmu/evals-skills

Made for: Claude Code.

Or install evals-skills, the plugin that ships this one along with the rest of its 7 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 error-analysis

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/hamelsmu/evals-skills/error-analysis"><img src="https://agentmods.dev/badge/skills/hamelsmu/evals-skills/error-analysis.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,745 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. Third-party audits
  • Socket pass 15 Sept 2026
  • Snyk pass 15 Sept 2026
How audits are shown
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 $0.00053 $0.01745
Opus 5.5 $0.00021 $0.00698
Sonnet 5.5 $0.00011 $0.00349
Haiku 4.5 $0.00005 $0.00175

Measured 1mo ago against content hash 2689164e29e3, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

error-analysis 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 1mo 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

2 near-identical copies found in the catalogue:

skills/error-analysis/SKILL.md · 165 lines

How it starts

The opening of the file, as written. The whole thing — 165 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Error Analysis

Guide the user through reading LLM pipeline traces and building a catalog of how the system fails.

Overview

  1. Collect ~100 representative traces
  2. Read each trace, judge pass/fail, and note what went wrong
  3. Group similar failures into categories
  4. Label every trace against those categories
  5. Compute failure rates to prioritize what to fix

Core Process

Step 1: Collect Traces

Capture the full trace: input, all intermediate LLM calls, tool uses, retrieved documents, reasoning steps, and final output.

Target: ~100 traces. This is roughly where new traces stop revealing new kinds of failures. The number depends on system complexity.

From real user data (preferred):

  • Small volume: random sample
  • Large volume: sample across key dimensions (query type, user segment, feature area)
  • Use embedding clustering (K-means) to ensure diversity

From synthetic data (when real data is sparse):

  • Use the generate-synthetic-data skill
  • Run synthetic queries through the full pipeline and capture complete traces

Step 2: Read Traces and Take Notes

Present each trace to the user. For each one, ask: did the system produce a good result? Pass or Fail.

For failures, note what went wrong. Focus on the first thing that went wrong in the trace — errors cascade, so downstream symptoms disappear when the root cause is fixed. Don't chase every issue in a single trace.

Write observations, not explanations. "SQL missed the budget constraint" not "The model probably didn't understand the budget."

Template:

| Trace ID | Trace | What went wrong | Pass/Fail |
|----------|-------|-----------------|-----------|
| 001      | [full trace] | Missing filter: pet-friendly requirement ignored in SQL | Fail |
| 002      | [full trace] | Proposed unavailable times despite calendar conflicts | Fail |
| 003      | [full trace] | Used casual tone for luxury client; wrong property type | Fail |
| 004      | [full trace] | - | Pass |

Read the full file on GitHub · 165 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. 1mo ago First seen · 165 lines · 53 tokens per session scan A 2689164e29e3

Subscribe to this mod's changes

error-analysis is a skill published in the GitHub repository hamelsmu/evals-skills (1,676 stars, last pushed 2mo ago), licensed MIT. It adds 53 tokens to every session and 1,745 once invoked, about $0.0002 per session on Opus 5.5. 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.

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