Anthropic has released Claude Fable 5, the publicly accessible version of its Mythos-class model, priced at $10/$50 per million input/output tokens — double Claude Opus 4.8 and double GPT-5.5's input price. Claude Mythos 5 is the same underlying model but without safety classifiers, restricted to approved government and biomedical partners. Fable 5 includes classifier-based fallbacks that reroute sensitive cybersecurity and biology queries to Opus 4.8. On benchmarks, Fable 5 leads with 80.3% on SWE-Bench Pro vs GPT-5.5's 58.6% and Opus 4.8's 69.2%, and shows strong token efficiency on complex reasoning tasks. However, for high-volume, well-defined workloads, Opus 4.8 or Sonnet 4.6 offer better economics. Subscription users get free access through June 22, after which usage credits are required. There is no batch/async pricing tier, giving GPT-5.5 a cost advantage for offline processing at scale.
