Fable 5.2 flips the table late at night! Building an operating system from scratch, with cost-effectiveness surpassing Opus 5.5

What happened: Anthropic released Claude Fable 5.2 and Mythos 5.2, with Fable 5.2 demonstrated building a full operating system from an empty folder using over 1000 agents running for 8 days without human code input. Key numbers: Generation speed up 30% versus 5.1; API pricing cut 20% to $8 per million input tokens Why it matters: Anthropic says Fable 5.2 at High tier matches Opus 5.5's max performance at roughly half the cost per task, and recommends using it as an Advisor or Orchestrator for harder work. Anthropic also limited the models' RSI abilities during training to Opus 5.5 levels.

Anthropic released Claude Fable 5.2 and Mythos 5.2, with Fable 5.2 demonstrated building a full operating system from an empty folder using over 1000 agents running for 8 days without human code input.

Anthropic says Fable 5.2 at High tier matches Opus 5.5's max performance at roughly half the cost per task, and recommends using it as an Advisor or Orchestrator for harder work. Anthropic also limited the models' RSI abilities during training to Opus 5.5 levels.