Claude Opus 5.5 is now available on B.AI, with API and Web Chat opening together

Claude Opus 5.5 is now available on B.AI, with the API and Web Chat opening at the same time. Model details are in the Claude Opus 5.5 documentation.

B.AI says the model is the first in AnthropicAI’s newly released Claude 5.5 series, built for long-running agent coding and complex knowledge work. On most tasks it reaches Claude Fable 5.1 performance, costs about 40% less to run than Opus 5, and supports a 1M-token context with up to 128K output. B.AI also says the model shows leading capability in Computer Use and multi-step automation.