Anthropic releases Fable 5 with mandatory safeguards

Summary

Benchmark gains are real—Stripe modernized 50M lines of Ruby in one day versus two months of team time—but guardrails trade capability for safety, and mandatory data retention blocks privacy-sensitive workloads.

Why it matters

Benchmark gains are real—Stripe modernized 50M lines of Ruby in one day versus two months of team time—but guardrails trade capability for safety, and mandatory data retention blocks privacy-sensitive workloads.

Sources

1. 1.Fable scores 80% (and Mythos 5, without the guardrails, 80.4%)
2. 2.Stripe, for example, had Fable 5 modernize a 50-million-line Ruby codebase in one day — something the company says would've otherwise taken a team of developers two months
3. 3.using those models means opting in to 30-day data retention — or not using them at all
4. 4.stay "focused across millions of tokens in long-running tasks and improve its outputs using its own notes"
5. 5.$10 per million input tokens and $50 per million output tokens. That's twice the price of Anthropic's current Opus model