Claude Fable 5 debuts as safety-tuned Mythos variant at $10/$50 per million tokens

Anthropic released Claude Fable 5 on June 9, a Mythos-class model built with additional safety guardrails for general use. The model is now live in the Claude API at $10 per million input tokens and $50 per million output tokens.

Fable 5 is a restricted version of Claude Mythos 5, Anthropic's flagship Mythos-class architecture. The company has not disclosed parameter count or context length. Subscribers can access Fable 5 through June 22; after that date, all usage requires purchasing credits.

What stands out

1. 01Mythos-class foundation: Fable 5 is the first publicly available model built on Anthropic's Mythos-class architecture, though the company has withheld technical specifications.
2. 02Safety-tuned variant: Anthropic describes Fable 5 as "made safe for general use," indicating additional content filters and behavioral constraints compared to the unrestricted Mythos 5 model.
3. 03Premium API pricing: At $10 per million input tokens and $50 per million output tokens, Fable 5 sits in the same tier as Claude Opus 3.5.
4. 04Time-limited subscriber access: Claude Pro and Team subscribers can use Fable 5 until June 22, 2026. After that, all users must pay per-token via credits.
5. 05No performance benchmarks: Anthropic's announcement includes no eval scores, parameter counts, or comparisons to prior Claude models—a departure from the company's typical release pattern.