eval-breakdown

A diagnostic workflow for understanding why an AI-agent evaluation received its scores. An agent evaluation is a test of an AI agent's behavior across defined questions or tasks.

In plain words
What is it for?
Use it to audit evaluation runs question by question, study low-score patterns, and investigate conflicts such as reusing memory while still showing traceable evidence.
Why use it?
It connects individual scores and judge explanations with the agent's full conversation and tool-use traces, making causes easier to investigate.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/googlecloudplatform/professional-services/eval-breakdown
Any agent
npx skills add GoogleCloudPlatform/professional-services --skill eval-breakdown
Clone the repo
git clone --depth 1 https://github.com/GoogleCloudPlatform/professional-services

Made for: Claude Code, Codex.

Per session 100 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 727 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00100 $0.00727
Opus 5 $0.00050 $0.00364
Sonnet 5 $0.00020 $0.00145
Haiku 4.5 $0.00010 $0.00073

Measured yesterday against content hash 6b7cafb1d9a8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

eval-breakdown 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 yesterday.

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.

tools/agent-eval/skills/eval-breakdown/SKILL.md · 57 lines

How it starts

The opening of the file, as written. The whole thing — 57 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Eval Breakdown: Question-by-Question Diagnostic Analysis

This skill guides an agent through conducting a rigorous, evidence-grounded, question-by-question narrative diagnostic audit of an agent-eval benchmark run.


1. Input Sources & Directory Anatomy

An agent-eval results folder (tests/eval/results/{run_id}/ or gs://<bucket>/runs/{run_id}/) contains three primary diagnostic artifacts:

  1. eval_summary.json: Aggregated metrics, per-question score distributions, and AutoRater judge verdicts.
  2. question_answer_log.md: Multi-turn conversational transcripts including user prompts, agent responses, tool calls, and tool outputs.
  3. gemini_analysis.md: Automated executive diagnosis and loss cluster summary.

2. Step-by-Step Diagnostic Workflow

Step 1: Generate the Baseline Matrix Table

Extract individual question scores and judge reasoning using the bundled script:

python3 tools/agent-eval/skills/agent-eval/scripts/parse_eval_summary.py \
  --summary-path tests/eval/results/{run_id}/eval_summary.json

Step 2: Perform the Dialogue Audit Protocol

Inspect question_answer_log.md for each scenario, analyzing across:

  1. Turn-by-Turn User Intent: What the user requested in Turn 1, Turn 2, etc.
  2. Tool Execution & Traceability: Did the agent emit SQL/API tool calls on each turn where factual assertions were made, or did it answer from empirical dialogue memory?
  3. The Memory Reuse vs. Traceability Rubric Clash:
    • Diagnostic Pattern: If tool_use_quality drops to 0.00 on Turn 2 follow-ups, verify if the agent answered correctly from dialogue memory without re-querying the backend. If the rubric expects a tool call on every turn, calibrate the rubric or prompt instructions accordingly.
  4. Judge Explanation Grounding: Cross-reference any rubric score $< 1.00$ against the exact model response to verify whether the deduction was a genuine agent failure (Tier 1) or an overly strict judge rubric (Tier 2).

Read the full file on GitHub · 57 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. yesterday First seen · 57 lines · 100 tokens per session scan A 6b7cafb1d9a8

Subscribe to this mod's changes

eval-breakdown is a skill published in the GitHub repository GoogleCloudPlatform/professional-services (3,065 stars, last pushed 10d ago), licensed Apache-2.0. It adds 100 tokens to every session and 727 once invoked, about $0.0005 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 2026-08-30.

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