Claude Sonnet 5.5 Now Available

Claude Sonnet 5.5 is now available with experimental support across the Kiro IDE, CLI, Crew, and Web for Pro, Pro+, Pro Max, and Power customers in us-east-1 (IAD) and eu-central-1 (FRA). It's Anthropic's fastest Sonnet model to date and a clear upgrade over Sonnet 5: output is more than 30% faster, real-world knowledge work approaches Opus 5.5 performance, and clearer writing makes it a stronger collaborator. Claude Sonnet 5.5 includes a 1M-token context window, adaptive thinking on by default, and a 1.3x credit multiplier. To load the latest model list, restart the IDE or CLI, run kirocrew restart for Crew, or refresh Web in your browser. Learn more ->