Anthropic Claude Sonnet 5.5 and Claude Opus 5.5 are now available on Kiro in AWS GovCloud (US)
Anthropic has launched new models on Kiro for AWS GovCloud (US), with Opus 5.5 offering 40% fewer tool calls for long-running coding tasks and Sonnet 5.5 providing over 30% faster output.
Anthropic's new models, claude sonnet 5.5 and claude opus 5.5, are now available in the AWS GovCloud (US) region via Kiro IDE and CLI. Opus 5.5, anthropic's most capable opus model to date, advances agent-based coding for long tasks, completing tasks in about 40% fewer tool calls and half the context of opus 5. It offers a 1M context window and a 2.0x credit multiplier (down from opus 5's 2.2x). Sonnet 5.5, anthropic's fastest sonnet model, provides a natural upgrade for existing sonnet 5 users, with outputs over 30% faster and real-world coding and knowledge work approaching opus 5.5 performance. It features a 1M context window and a 1.3x credit multiplier. Update and restart your IDE or CLI to access the new models from the model selector. For details, see GovCloud docs, monitoring and tracking guides, or contact your AWS account team. Learn more about Kiro at the Kiro product page.
Why it matters
This update impacts developers and organizations using AI models in AWS GovCloud (US), especially those engaged in long-running coding tasks or high-throughput knowledge work.