Anthropic Claude Sonnet 5.5 and Claude Opus 5.5 are now available on Kiro in AWS GovCloud (US)

Two new Anthropic models are now available in the Kiro IDE and CLI for the AWS GovCloud (US) Regions. Claude Opus 5.5 is Anthropic’s most capable Opus model yet and a step up from Opus 5 on long-running agentic coding work. Opus 5.5 thinks adaptively on every request, deciding how much effort each task needs, and completes tasks with roughly 40% fewer tool calls and about half the tokens of Opus 5 in Kiro’s internal benchmarking.