AWS adds Claude Opus 5.5 and Sonnet 5.5 to Kiro in GovCloud

AWS says Claude Opus 5.5 and Claude Sonnet 5.5 are now available in Kiro's coding interface and command-line tool in AWS GovCloud (US). Both models have a 1M context window, allowing them to process large amounts of information in one request. In Kiro's internal benchmarks, Opus 5.5 used roughly 40% fewer tool calls and about half the tokens of Opus 5. Its credit multiplier falls from 2.2x to 2.0x. AWS says Sonnet 5.5 produces output more than 30% faster than Sonnet 5 and has a 1.3x credit multiplier. Developers must update and restart their Kiro software to access the models.