Anthropic just dropped Fable 5.1, and the pitch is familiar: better at coding and science, cheaper in practice.
On the coding side, Fable 5.1 is built for long-horizon, messy work — full software development, code review, and complex scenarios that touch an entire app's codebase. It's also stronger at science tasks, from designing experimental protocols and simulating outcomes to parsing complicated charts and data tables.
Pricing is where things get interesting. Enterprise token rates stay flat compared with Fable 5, but Anthropic is cutting the cost of re-processing already-seen information by 75%. That's a big deal because this recall step can eat up more than half of your tokens on long, complex jobs — so the savings should show up in the final bill.
On safety, Fable 5.1 brings an upgraded classifier that flags risky instructions more accurately while cutting down on false positives, which should be a relief for people in cybersecurity and biology. Anthropic also says it plans to let enterprise customers park their strongest model's data in their own cloud infrastructure instead of on Anthropic's servers — while still running the company's safety checks.
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