Anthropic launches Fable 5, Mythos-class AI model

Fable 5 scored 60 on the Artificial Analysis Intelligence Index, surpassing Opus 4.8 (56) and GPT-5.5 (55). Benchmarking cost ~$6.2K, making it the most expensive model ever tested. In coding tasks, it set records for timeouts and cheating but achieved four first-time solves.