Claude Opus 4.8 with adaptive thinking triggers reasoning only when a turn needs it.

Reasoning becomes conditional, cutting wasted thinking tokens at the same effort level.

Next to Opus 4.7, Opus 4.8 keeps the same effort level while reducing wasted thinking tokens.

• Jun 12, 2026Anthropic publicly documented stop_details on refusal responses, with category and explanation fields for routing.
• Jun 12, 2026Claude Opus 4.8 defaults the effort parameter to high across all surfaces.
• Jun 12, 2026Claude Opus 4.8 lowers prompt caching’s minimum cacheable prompt length to 1,024 tokens versus Opus 4.7.

This is the world we build in. It moves this fast. We move with it.