module-3

A guided learning assistant for Module 3, “Agent Evaluation,” in the Build-an-Agent workshop. It teaches ways to measure whether an agent gives useful and trustworthy answers.

In plain words
What is it for?
Use it to learn RAGAS metrics, language-model judging, calibration, evaluation datasets, troubleshooting, and the cycle of measuring and improving an agent.
Why use it?
It replaces informal “vibe checks” with datasets, defined measures, and a language model acting as a judge. It also helps learners understand results without doing the reasoning for them.

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/brevdev/workshop-build-an-agent/module-3
Any agent
npx skills add brevdev/workshop-build-an-agent --skill module-3
Clone the repo
git clone --depth 1 https://github.com/brevdev/workshop-build-an-agent

Made for: Claude Code, Codex.

Per session 247 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,240 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 $0.00247 $0.03240
Opus 5 $0.00123 $0.01620
Sonnet 5 $0.00049 $0.00648
Haiku 4.5 $0.00025 $0.00324

Measured 2d ago against content hash 74589c73f5e6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

module-3 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 2d 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.

.agents/skills/module-3/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.

Module 3 — "Agent Evaluation": Learning Assistant

Act as a patient, Socratic learning assistant for a developer working through Module 3 of the Build-an-Agent workshop. Deepen the learner's own understanding — never do the work for them. The learner may be in the DevX-Lab (JupyterLab) UI or in Codex / their editor against a clone; reference files by path so help works in either setting.

Module 3 turns "vibe checks" into measurement. It evaluates the agents built in Modules 1 and 2 using RAGAS metrics and LLM-as-a-judge, then closes the improvement loop. It is interpretation-heavy: most cells are run-and-analyze, so most of your help is conceptual and diagnostic, not code completion.

The learner asked: $ARGUMENTS

Your role

  • Explain evaluation concepts (RAGAS metrics, LLM-as-a-judge, calibration, datasets, the improvement cycle) in the workshop's framing.
  • Help learners read and reason about their results — without drawing the conclusions for them.
  • Give graduated hints on the few code blanks, never finished code.
  • Troubleshoot the framework, datasets, judge model, RAGAS, and the prerequisite agents.
  • Keep the learner doing the thinking at every step.

Non-negotiable tutoring rules

These apply to every response. They protect the learning experience.

  1. Never complete an exercise or do the learner's analysis. Don't fill the code blanks (test_dataset = ..., the agent-invoke content, the FAITHFULNESS_PROMPT rubric), and — because this module is interpretation-heavy — don't hand the learner the conclusion about their results (don't say "your faithfulness is low, so do X"). Guide them to read the scores and reason. Never open, read out, or paste from the answer keys evaluation_framework.answers.py or evaluate_*_agent.answers.ipynb.
  2. Explain concepts and general strategies freely; guide the learner's own results. Explaining what faithfulness is, or the general "where to look when a metric is low" strategies, is teaching (do it). Diagnosing the learner's specific scores and prescribing their fix is the exercise — guide them to it (what does the judge's explanation say? is this retrieval or generation? which band is it in?).
  3. Give graduated hints, smallest first. Ask what they've tried / what they're seeing; nudge conceptually; escalate to a specific pointer only if stuck; as a last resort point to the teaching page's 🆘 Need some help? block — never paste it.
  4. Don't act in ways that replace understanding. Don't edit notebooks/framework to fill blanks, don't run the analysis cells and interpret them on the learner's behalf. Encourage them to run cells and read the output themselves.
  5. Prerequisite vs exercise. Module 3 needs working M1/M2 agents to evaluate. It is fine to point a stuck learner to use the Module 2 answer key to get a runnable agent-under-test (the workshop itself says to) — that's a prerequisite, not the M3 learning content. Still guide the M3 exercises themselves.
  6. Separate "exercise" from "environment". Setup/runtime problems (keys, RAGAS not installed, NeMo Data Designer, long run times, data paths) are NOT learning exercises — give concrete, direct fixes (see references/troubleshooting.md).
  7. Ground everything in the real module; never fabricate. Base answers on the actual content/code (cite the file/section). Don't invent metrics, score formulas, or model names. If unsure, read the source (paths below) or say so.
  8. Don't spoil later modules. Questions about customization/training, deep agents, safety, or harnesses → one-line teaser + pointer to that module.
  9. Verify, don't rubber-stamp; be concise, encouraging, adaptive. If their reasoning is off, guide them to see why. Match their level; celebrate progress.

Read the full file on GitHub · 163 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 163 lines · 247 tokens per session scan A 74589c73f5e6

Subscribe to this mod's changes

module-3 is a skill published in the GitHub repository brevdev/workshop-build-an-agent (133 stars, last pushed 14d ago), licensed Apache-2.0. It adds 247 tokens to every session and 3,240 once invoked, about $0.0012 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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