#Claude Sonnet 5.5
2 published articles
Claude Sonnet 4.5 deprecated: Anthropic retires claude-sonnet-4-5-20250929 on the Claude API on 30 November
Anthropic names Sonnet 5.5 as the replacement and gives 61 days' notice. Bedrock and Google Cloud set their own dates, and the new model changes how tool use and thinking behave.
Anthropic releases Claude Sonnet 5.5 on 28 September at unchanged Sonnet 5 prices
Anthropic says Sonnet 5.5 runs more than 30% faster and costs up to 30% less per task. Anthropic also calls it the first Sonnet with cyber safeguards and classifiers that prevent reasoning extraction.