agent skill — A reusable instruction file that teaches an agent how to do one job well — the procedure, the tools, and what counts as done.
eval — A repeatable test for AI quality — a set of tasks plus scoring — used the way software teams use test suites, because model output is too variable to judge by eyeballing.
Why it matters
If evalA repeatable test for AI quality — a set of tasks plus scoring — used the way software teams use test suites, because model output is too variable to judge by eyeballing.Full definition → rather than training is now the bottleneck, leverage shifts to choosing the right tasks and building benchmarks that reflect real utility — closer to product judgment than to research.