Fable 5.1, Now Live in Harvey
By Steven Van ·
Announcing Fable 5.1 in Harvey.
Harvey customers can now opt in to Claude Fable 5.1, Anthropic's latest model, Harvey said in an announcement published September 1, 2026. Customers who already opted in to Fable 5 will get Fable 5.1 access this week.
In Harvey's early testing, Fable 5.1 was strongest on complex, document-heavy analysis, with the biggest quality gain over Fable 5 on litigation and dispute resolution work. It also performed well on data privacy and cybersecurity tasks and on capital markets tasks. At its lowest reasoning setting, Fable 5.1 stayed thorough while using roughly half the output tokens, which Harvey says matters for high-volume work such as reviewing agreements. Full results against Harvey's Legal Agent Benchmark are on the Artificial Analysis and Vals leaderboards.
Harvey outlined a few things customers should know before enabling it:
- Using Fable 5 or Fable 5.1 may involve data processing practices that differ from existing customer agreements.
- Eligible customers can use both models with zero data retention under a time-bound exemption while Anthropic rolls out Enterprise Frontier Safeguards, which will let eligible customers store data in cloud infrastructure controlled by Harvey or by the customer.
- Anthropic does not offer regional processing for Fable 5 or 5.1, so all data is processed in the United States.
- Access is opt-in, not default.
