Claude Opus 5 Introduces Five Effort Levels with Default Reasoning

Claude Opus 5 operates as five models in one endpoint with five effort levels. Reasoning is enabled by default, and it cannot be turned off when using the xhigh or max levels without triggering an API error.

2026-07-25 ~ 2026-07-25 · 2 related posts

• Claude Opus 5 adds five effort levels and defaults to reasoning on — rohanpaul_ai · 2026-07-25
• Claude Opus 5 defaults reasoning on and can reject xhigh or max without it — rohanpaul_ai · 2026-07-25