Claude Opus 5.5 opens at $4 per million input tokens

Anthropic released Claude Opus 5.5 at $4 per million input tokens and $20 per million output tokens, down from Opus 5’s $5 and $25 while retaining a 1M-token context and 128K maximum output. Its migration notes list four breaking changes, including always-on adaptive thinking and a different computer-use tool on Claude API and Google Cloud. Builders pricing long-running agents should compare this drop with MiMo’s output-price gap before switching; cheaper tokens do not erase migration work.