Claude Opus 5.5 improves agentic coding efficiency with adaptive effort management, resulting in approximately 40% fewer tool calls and half the token usage compared to Opus 5. Sonnet 5.5 is Anthropic's fastest Sonnet model, offering over 30% speed increase and clearer writing for enhanced collaboration.
Both models support a 1 million token context window and are available with different credit multipliers to balance cost and capability. They cater to developers needing advanced language model performance within the AWS GovCloud environment.
Source & further reading
Anthropic Claude Sonnet 5.5 and Claude Opus 5.5 are now available on Kiro in AWS GovCloud (US) ↗Source published 2026-10-09. This report was prepared with AI assistance from the linked primary-source material. Claims and limitations should be checked against the original announcement or research.