AI Evaluation and Fine-Tuning Methodology Skill

Core stance: an eval is an instrument. An untrusted instrument is worse than no instrument, because it produces confident wrong numbers that ship regressions. Fine-tuning is an optimization loop around that instrument. If the instrument is weak, training just makes the model better at gaming bad measurement. This skill is the cross-domain methodology layer that domain eval and model-lifecycle skills defer to: how to keep an LLM-as-judge honest, integrate eval frameworks, choose between prompting/context/tools/test-time compute/SFT/preference/RFT/PEFT/ distillation, derive thresholds instead of guessing them, and stop flaky runs or training leakage from masquerading as progress.

This is the methodology umbrella for evals. Domain skills own what to measure; this skill owns whether you can trust the measurement.