Opus 5 FrontierCode score drops from 53.4% to 48% in new card

Developer Andrew Carr flagged an evaluation discrepancy: Claude Opus 5 reported 53.4% on FrontierCode at launch, but the latest 5.5 model card shows only 48%, raising questions about Anthropic's benchmark methodology.

2026-09-23 ~ 2026-09-23 · 2 related posts

• Opus 5 scored 53.4% on FrontierCode at launch, but its new card shows just 48% — andrew_n_carr · 2026-09-23
• Opus 5 Scored 53.4% on FrontierCode at Launch, Just 48% on the 5.5 Card — mathemagic1an · 2026-09-23