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Eval-Driven Development for LLM Apps

Builds automated pixie-based evaluation pipelines to score a Python LLM app's behavior with real runs

Stars
40,703
Licence
MIT
Files
15 files

What it does

When installed, the agent sets up an automated quality-testing pipeline for a Python application that calls an LLM. It runs the real app with test inputs, scores outputs with evaluators such as LLM-as-judge or similarity checks, and produces pass/fail results through a pixie test run, then proposes concrete fixes. It is built around pixie-qa, a separate Python package, and starts a local web server so you can view results.

Great for

  • Python developers who maintain an LLM-powered app and want regression tests for its behavior
  • Teams that need eval datasets and scoring for prompt or context-assembly changes
  • People who want an agent to add QA to an existing project without mocking the LLM

Skip it if

  • Projects that are not Python or do not call an LLM, since the skill targets Python LLM applications
  • Users who only want unit tests with mocked LLM responses, because the skill explicitly forbids mocking the LLM in evals
  • Environments where installing packages, running scripts and starting a background web server are not acceptable, since the workflow does all three

Try asking

  • “Set up QA with evals for my Python chatbot project”
  • “Add evaluators and a golden dataset to test my RAG app's answers”
  • “Benchmark my LLM app and tell me what to fix”
  • “Run the existing pixie evals again and show me the scores”
Step-by-step guide: how to use Eval-Driven Development for LLM AppsInstall, first run, examples, tips and FAQs

Install in 3 steps

  1. 1

    Download the skill

    The ZIP contains the 15 original files, the MIT licence and an attribution note.

    eval-driven-dev.zip
  2. 2

    Add it to your agent

    Claude Code (all projects)

    mkdir -p ~/.claude/skills && unzip eval-driven-dev.zip -d ~/.claude/skills/

    Claude Code / Agent SDK (this project only)

    mkdir -p .claude/skills && unzip eval-driven-dev.zip -d .claude/skills/

    Claude apps (web/desktop): Settings → Capabilities → Skills → Upload skill, and choose the ZIP.

  3. 3

    Ask for the task

    No special command needed — the agent reads the skill's description and loads it when your request matches. Try one of the prompts above.

Get better results

  • Make sure the app's required environment variables and API keys are set before starting, since the skill stops and asks for help if they are missing
  • Provide any spec file or dataset you want used, because the skill reads referenced files first and uses them as the basis for the eval
  • Review the generated dataset and evaluators, since LLM-as-judge scores can be noisy

What's inside

  • references/1-a-project-analysis.md
  • references/1-b-entry-point.md
  • references/1-c-eval-criteria.md
  • references/2a-instrumentation.md
  • references/2b-implement-runnable.md
  • references/2c-capture-and-verify-trace.md
  • references/3-define-evaluators.md
  • references/4-build-dataset.md
  • references/5-run-tests.md
  • references/6-analyze-outcomes.md
  • references/evaluators.md
  • references/runnable-examples/cli-app.md
  • references/runnable-examples/fastapi-web-server.md
  • references/runnable-examples/standalone-function.md
  • SKILL.md

Redistributed unmodified from github/awesome-copilot under the MIT licence. The assessment was drafted with AI from the skill's files on 2026-10-29. Skills can instruct your agent to run code — read SKILL.md and any scripts before installing.