
Phoenix Evals
OfficialFreeBuild and validate evaluators for AI applications.
Free · Opens the source repo
What Phoenix Evals does
Phoenix Evals is designed for developers and data scientists who want to create and validate evaluators for AI and LLM applications. The skill emphasizes a code-first approach, enabling users to build evaluators that can assess the performance and accuracy of AI models. By integrating human validation into the evaluation process, Phoenix Evals ensures that the evaluators are not only automated but also reliable.
The skill provides a structured workflow that guides users through the process of setting up their environment, selecting evaluation criteria, and building both code and LLM evaluators. It includes comprehensive references for Python and TypeScript, making it versatile for different programming environments. Users can choose from pre-built evaluators or create custom ones tailored to their specific needs, enhancing the flexibility of the evaluation process.
In addition to building evaluators, Phoenix Evals offers tools for error analysis and validation. Users can analyze errors through detailed tracing and sampling, categorize failures, and validate the accuracy of their evaluators against human labels. This focus on validation helps ensure that the evaluators are effective and can be trusted in production environments.
Overall, Phoenix Evals is a valuable resource for anyone involved in developing AI applications, providing the necessary tools and references to build robust evaluators that meet industry standards.
When to use it
Use Phoenix Evals when you need to create evaluators for AI models and want to ensure they are validated against human standards.
When not to use it
This skill may not be suitable for those looking for a fully automated evaluation solution without any human oversight or validation.
What you can build with it
Setting Up an Evaluator
Begin with the setup guides for Python or TypeScript, then follow the workflow to build your first evaluator.
Running Experiments
Use the experiments section to create datasets and run evaluations, helping you fine-tune your AI models.
Error Analysis
Implement error analysis techniques to identify and categorize failures in your AI applications, improving overall performance.
How to install Phoenix Evals
View source1. Install with the skills CLI
npx skills add github/awesome-copilot/phoenix-evals --agent claude-code2. Or install it manually
Download the skill folder and drop it into ~/.claude/skills/ for all projects, or .claude/skills/ to scope it to one repo. Restart Claude Code so it picks up the new skill.
Anthropic's agentic coding CLI, and the reference implementation of Agent Skills. Drop a skill folder into ~/.claude/skills and Claude Code loads it automatically whenever a task matches the skill's description. Claude Code docs
Inside SKILL.md
Written by githubPhoenix Evals
Build evaluators for AI/LLM applications. Code first, LLM for nuance, validate against humans.
Quick Reference
Workflows
Starting Fresh: observe-tracing-setup → error-analysis → axial-coding → evaluators-overview
Building Evaluator: fundamentals → common-mistakes-python → evaluators-{code|llm}-{python|typescript} → validation-evaluators-{python|typescript}
RAG Systems: evaluators-rag → evaluators-code-* (retrieval) → evaluators-llm-* (faithfulness)
Production: production-overview → production-guardrails → production-continuous
Reference Categories
| Prefix | Description |
|---|---|
fundamentals-* | Types, scores, anti-patterns |
observe-* | Tracing, sampling |
error-analysis-* | Finding failures |
axial-coding-* | Categorizing failures |
evaluators-* | Code, LLM, RAG evaluators |
experiments-* | Datasets, running experiments |
validation-* | Validating evaluator accuracy against human labels |
production-* | CI/CD, monitoring |
Key Principles
| Principle | Action |
|---|---|
| Error analysis first | Can't automate what you haven't observed |
| Custom > generic | Build from your failures |
| Code first | Deterministic before LLM |
| Validate judges | >80% TPR/TNR |
| Binary > Likert | Pass/fail, not 1-5 |
Frequently asked questions about Phoenix Evals
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