Anthropic launches Claude Sonnet 5.5: 30% faster than Sonnet 5 at the same $2/$10 pricing

ClaudeDevs · x · 2026-09-29

Anthropic's ClaudeDevs account announced Claude Sonnet 5.5: same pricing as Sonnet 5 ($2/$10 per million tokens, cache reads $0.20), 30% faster with up to 30% lower cost for most workloads. Thinking is always on by default (adaptive), with betweentools to disable upfront thinking. A migration guide details breaking changes—thinking budgets, sampling parameters, assistant prefill, forced tool choice, and disabled thinking all return 400 errors—and a new outputconfig effort setting. Context window remains 1M tokens.

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