Introducing Claude Opus 5.5, the first model in our new Claude 5.5 family. It performs at the level of Claude Fable 5.1 for most tasks, and costs 40% less to run than Opus 5.↗·@claudeai·Sep 22, 2026·model-release·claude-5-5·claude-fable-5-1·claude-opus-5-5·inference-cost