Claude Opus 5.5 is available as the first Claude 5.5 model
Claude Opus 5.5 is available, Anthropic said on September 22, 2026. Claude describes Opus 5.5 as the first model in the new Claude 5.5 family.
Claude says the model performs at the level of Claude Fable 5.1 for most tasks and costs 40% less to run than Opus 5.