Anthropic Fable 5 Now Available for Early Access in Harvey

A new AI model has been made available to customers of the legal technology platform, Harvey. The model, known as Anthropic's Fable 5, is part of the Claude family and offers improved performance on complex legal tasks compared to its predecessor.

Fable 5 achieved a score of 13.3% on the Legal Agent Benchmark (LAB), which measures end-to-end completion of complex legal tasks under strict standards. This represents an all-time high-score for Harvey's customers, surpassing Opus 4.8's previous record of 10.4%. The model also performed well in internal evaluations using BigLaw Bench, a proprietary benchmark developed by Harvey.

The use of Fable 5 involves data processing practices that differ from those outlined in existing customer agreements with Harvey. Specifically, Anthropic will retain data and contents for up to 30 days, unless longer retention is required for safety or legal reasons. Customers can opt-in to early access to the model, which will be monitored during this period.

According to internal evaluations by lawyer evaluators, Fable 5 excelled in drafting and markup analysis tasks. The model produced well-structured documents across various practice areas and accurately identified term sheet deviations, off-market provisions, and internal inconsistencies when reviewing counterparty redlines. However, performance on complex quantitative analysis was more mixed.

Harvey customers can access the new AI model by opting-in through their account team. It's worth noting that Fable 5 will be processed in the United States, as regional processing is not offered by Anthropic.