Adaptive thinking is the recommended way to use extended thinking with Claude Opus 4.7, Claude Opus 4.6, and Claude Sonnet 4.6, and is the default mode on Claude Mythos Preview (where it auto-applies whenever thinking is unset). Instead of manually setting a thinking token budget, adaptive thinking lets Claude dynamically determine when and how much to use extended thinking based on the complexity of each request. On Claude Opus 4.7, adaptive thinking is the only supported thinking mode; manual thinking: {type: "enabled", budget_tokens: N} is no longer accepted.
From https://platform.claude.com/docs/en/build-with-claude/adapti...:
Adaptive thinking is the recommended way to use extended thinking with Claude Opus 4.7, Claude Opus 4.6, and Claude Sonnet 4.6, and is the default mode on Claude Mythos Preview (where it auto-applies whenever thinking is unset). Instead of manually setting a thinking token budget, adaptive thinking lets Claude dynamically determine when and how much to use extended thinking based on the complexity of each request. On Claude Opus 4.7, adaptive thinking is the only supported thinking mode; manual thinking: {type: "enabled", budget_tokens: N} is no longer accepted.