ai-evals

ai-evals is a skill for Claude Code, Codex from liqiongyu/lenny_skills_plus. It costs 46 tokens per session (2,076 once invoked), scanned A, original, Apache-2.0.

A structured way to test the quality of features that use large language models, such as chat assistants or copilots. It defines good results, creates example tests, sets judging rules and tracks failures over time.

In plain words
What is it for?
Use it to create an evaluation plan, test set, scoring rubric and repeatable test process for an AI feature. It also turns new failures into future tests.
Why use it?
It replaces inconsistent impressions with repeatable checks, making it easier to compare prompts or models and catch regressions.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to create an evaluation plan, test set, scoring rubric and repeatable test process for an AI feature. It also turns new failures into future tests.

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

Made for: Claude Code, Codex.

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 ai-evals

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/liqiongyu/lenny_skills_plus/ai-evals"><img src="https://agentmods.dev/badge/skills/liqiongyu/lenny_skills_plus/ai-evals.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,076 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 $0.00046 $0.02076
Opus 5.5 $0.00018 $0.00830
Sonnet 5.5 $0.00009 $0.00415
Haiku 4.5 $0.00005 $0.00208

Measured 2mo ago against content hash 6327b078e7c0, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

ai-evals 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 2mo 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/ai-evals/SKILL.md · 125 lines

How it starts

The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AI Evals

Scope

Covers

  • Designing evaluation (“evals”) for LLM/AI features as an execution contract: what “good” means and how it’s measured
  • Converting failures into a golden test set + error taxonomy + rubric
  • Choosing a judging approach (human, LLM-as-judge, automated checks) and a repeatable harness/runbook
  • Producing decision-ready results and an iteration loop (every bug becomes a new test)

When to use

  • “Design evals for this LLM feature so we can ship with confidence.”
  • “Create a rubric + golden set + benchmark for our AI assistant/copilot.”
  • “We’re seeing flaky quality—do error analysis and turn it into a repeatable eval.”
  • “Compare prompts/models safely with a clear acceptance threshold.”

When NOT to use

  • You need to decide what to build (use problem-definition, building-with-llms, or ai-product-strategy).
  • You’re primarily doing traditional non-LLM software testing (use your standard eng QA/unit/integration tests).
  • You want model training research or infra design (this skill assumes API/model usage; delegate to ML/infra).
  • You only want vendor/model selection with no defined task + data (use evaluating-new-technology first, then come back with a concrete use case).
  • You want to measure overall product-market fit or retention, not AI output quality (use measuring-product-market-fit).
  • You need a product requirements document that includes but goes beyond eval design (use writing-prds).

Inputs

Minimum required

  • System under test (SUT): what the AI does, for whom, in what workflow (inputs → outputs)
  • The decision the eval must support (ship/no-ship, compare options, regression gate)
  • What “good” means: 3–10 target behaviors + top failure modes
  • Constraints: privacy/compliance, safety policy, languages, cost/latency budgets, timeline

Missing-info strategy

  • Ask up to 5 questions from references/INTAKE.md (3–5 at a time).
  • If details remain missing, proceed with explicit assumptions and provide 2–3 viable options (judge type, scoring scheme, dataset size).
  • If asked to run code or generate datasets from sensitive sources, request confirmation and apply least privilege (no secrets; redact/anonymize).

Read the full file on GitHub · 125 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. 2mo ago First seen · 125 lines · 46 tokens per session scan A 6327b078e7c0

Subscribe to this mod's changes

ai-evals is a skill published in the GitHub repository liqiongyu/lenny_skills_plus (53 stars, last pushed 5mo ago), licensed Apache-2.0. It adds 46 tokens to every session and 2,076 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.

Related

ai-evals compared with skills from other repositories

ai-evals next to 6 skills from other repositories
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ai-evalsliqiongyu/lenny_skills_plusSkill535mo agoApache-2.0A46Claude Code, Codex
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