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Error Analysis

This walks you through the unglamorous work of figuring out how your LLM system actually fails. You review about 100 traces, note what went wrong in each one, then group similar failures into 5-10 categories you can measure and fix. The process is deliberately manual at first because pre-defined failure lists cause confirmation bias. It pushes you to distinguish root causes (missing a filter in the SQL) from symptoms (wrong results downstream) and only build evaluators for failures that warrant the effort. Use it when starting evals, after big pipeline changes, or when production metrics tank and you need to know why.

skills.sh installs
799
GitHub stars
1.7K
last updated
Aug 21, 2026

Install

$ npx -y skills add hamelsmu/evals-skills --skill error-analysis --agent claude-code

Installs into .claude/skills of the current project.

Files

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

Sponsors

Details

Repository
github.com/hamelsmu/evals-skills
Categories
DevOps & CI/CD, AI & Agent Building, Debugging, Automation & Workflows, Sales & Marketing
First seen
Jun 3, 2026

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