Claude Fable 5.2 and Mythos 5.2

Anthropic's newest pair of top models, with Fable 5.2 now in the Claude Platform and Claude Code at a lower price than Fable 5.1.

Fable 5.2 is up to 30% faster than Fable 5.1 and costs $8 input and $40 output per 1M tokens, down from $10 and $50.
It is available in the Claude Platform and Claude Code. In Claude Code, claude-fable-5-2 is now the default Fable model with a 1M token context window, and saved Fable 5.1 picks move to the fable alias (use /model claude-fable-5-1 to switch back).
Effort defaults to high in the Claude Platform and medium in Claude apps. Anthropic says to save xhigh for the hardest long-running agent work and treat max as a way to find the ceiling, not for everyday use.
In Anthropic's examples, Fable 5.2 designed three working electronic devices from a one-paragraph prompt. It wrote the specifications, picked components, routed four-layer circuit boards, designed 3D-printable enclosures, and wrote the software, with each board ready for manufacture in under a day.
Mythos 5.2 launched alongside it. The launch posts do not state separate availability or pricing for Mythos 5.2.

Long, ambitious technical projects in coding, reasoning, and other fields where the model has to plan and build over many steps.

Switch from Fable 5.1 when speed or cost has been the limit on agent jobs, since 5.2 is faster and cheaper.

Developers and teams running long agent jobs in Claude Code or on the Claude API.

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