Hamel Husain

Trying the new Claude Eval tool

Published 2026-09-11 · Duration 58:39

Summary

The video provides a technical deep dive into the new Claude Evals tool, designed to evaluate the performance of AI plugins and skills. While the tool automates test case generation and scoring (comparing runs with and without the plugin), the speakers highlight significant limitations. The process is currently highly dependent on manual, pre-collected data (e.g., defining failure modes, providing positive/negative examples) and lacks an integrated, 'in-the-loop' annotation interface, making its real-world application challenging for robust build pipelines.

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Key takeaways

  1. Claude Plugin Eval Functionality 2:05

    The `Claude plugin eval` tool allows users to evaluate plugins by generating test cases, running the plugin against them, scoring the results, and comparing the scores with and without the plugin's intervention. This process generates a terminal output and an HTML report.

  2. Evaluation Input Requirements 10:10

    The tool requires users to define quality standards by providing examples of 'good' and 'bad' outputs, identifying specific failure modes (e.g., overediting, abrupt transitions, jargon), and supplying real prompts or past outputs.

  3. Process Limitations 31:40

    The current chat-based interface is criticized for being 'out of the loop.' Effective evaluation requires continuous, in-situ feedback and annotation, which the current tool does not adequately support.

Technical details

  • Claude Plugin Eval Command 125s

    The evaluation process is initiated by running the command `claude plugin eval` from the root directory of the plugins folder.

  • Evaluation Methodology 1400s

    The tool performs an ablation study, comparing the performance score of a skill/plugin (e.g., 'plain writing skill') when it is active versus when it is disabled (baseline).

  • Skill/Plugin Scope 350s

    The tool is designed to evaluate plugins, though the speakers questioned if it could evaluate standalone skills, noting that the plugin directory is the required execution context.

  • Data Requirements 1700s

    Effective use requires a comprehensive dataset of positive and negative test cases, detailed failure modes, and specific prompts to guide the evaluation process.

Mentioned resources

  • Claude plugin eval (Tool/Command)
  • plain writing skill (Skill/Plugin)
  • Claude Devs (Twitter) (Source)

Channel & topics

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