CW-301h · Module 3

Library Impact Metrics

3 min read

A prompt library is an investment. It takes time to build, maintain, and govern. The return on that investment should be measurable. Three metrics capture library impact: usage rate, output quality delta, and time savings.

Usage rate: what percentage of the team's Claude sessions use a library prompt? Below 30% means the library is not addressing the team's actual needs or the team does not know it exists. Above 70% means the library is deeply integrated into workflows. Output quality delta: compare deliverables produced with library prompts against deliverables produced with ad-hoc prompts. Measure revision cycles, stakeholder satisfaction, and factual accuracy. The library should produce measurably better output. Time savings: how much faster are library-prompt workflows compared to ad-hoc workflows? Measure end-to-end from task start to deliverable completion.

Do This

  • Track usage rate monthly — which prompts are used most and which are never used
  • Compare deliverable quality between library and ad-hoc workflows — the library should win
  • Retire prompts with zero usage for 90+ days — if nobody uses it, it is not solving a real problem

Avoid This

  • Measure library success by prompt count — 200 prompts that nobody uses is not success
  • Assume adoption without measurement — "I think people are using it" is not data
  • Ignore the prompts that are never used — they reveal gaps between what you built and what the team needs