Correct Answer, Weak Evidence: Measuring Multimodal Reasoning at the Fact Level
TL;DR for operators A correct multimodal answer with citations can still have a weak evidence trail. In human evaluation on Video-MMMU, Gemini-3-Pro reached 86% question-answering accuracy but only 16.3 on MuRGAt-Score, meaning answer performance and fact-level grounding ranked very differently. MuRGAt evaluates two requirements separately. Coverage asks whether verifiable claims receive citations. Attribution asks whether the cited frames, audio, figures, or temporal segments are actually relevant to and sufficient for the factual claims they accompany. The combined score rewards systems only when both conditions hold. ...