B.AI said Anthropic's Claude Fable 5.1 is now officially available through its API. According to ChainCatcher, the model uses the same underlying architecture as Claude Mythos 5.1 and is optimized for intensive coding, long-running agent workflows, and complex knowledge tasks.

The company said Claude Fable 5.1 scored 73.4% in CursorBench 3.2.0 under the highest compute setting. API access is now open to developers, with discounted pricing available through official channels and selected service providers.