Toronto, August 7, 2025 — Spellbook, the leading AI copilot for contracts, is now one of the first companies globally to integrate OpenAI’s newest frontier model, GPT-5, into its suite. The rollout is already underway, bringing dramatic improvements to contract revision and issue spotting workflows.

“Working with Spellbook on GPT-5 is the latest example of how their feedback and early testing will help us identify the API’s optimal impact where it matters most for transactional lawyers,” said Marc Manara, Head of Startups at OpenAI.

 

Unlocking Nuanced Issue Spotting

GPT-5 introduces a new level of sophistication in identifying subtle contractual risks. In internal tests, Spellbook found GPT-5 was the first model to consistently flag many nuanced, jurisdiction-specific compliance issues—that escaped earlier models like Claude 4 and GPT-4o.

The model demonstrates a deeper capacity to cross-reference jurisdiction, statutory requirements, and clause language, enabling a new level of automated legal diligence. Spellbook also noted significant advancements in GPT-5’s fluency with security, compliance, and data protection language, making it especially effective in refining and expanding enterprise-grade DPAs.

A Breakthrough in Surgical Document Revision

Beyond issue spotting, GPT-5 is setting a new benchmark for precision editing in complex Word documents—a critical task for transactional lawyers. Traditional generative models often regenerate entire sections or struggle with real-world Word document formatting. In contrast, GPT-5 is able to:

  • Make surgical edits that preserve surrounding context
  • Reliably populate key fields and remove placeholders
  • Accurately navigate and revise tabular structures in Word document agreements

“Transactional lawyers rarely draft from scratch. They work with legacy precedents that are often 50+ pages, full of defined terms, interlinked clauses, and embedded tables. GPT-5 is the first model we’ve seen that can reliably handle these realities,” said Scott Stevenson, co-founder and CEO of Spellbook.

Driving the Next Legal Workflow Evolution

Early results suggest GPT-5 will power an emerging class of revision-based workflows where AI acts more like an associate, carefully refining documents rather than spitting out isolated language. 

GPT-5 is now live in Spellbook Associate, Spellbook’s agentic drafting product, with phased deployment underway across Spellbook’s broader review functionality. The team is monitoring “suggestion acceptance rates” closely to optimize GPT-5’s rollout.

About Spellbook

Spellbook is the leading legal AI assistant built specifically for transactional lawyers. Integrated into Microsoft Word, Spellbook helps legal teams draft, review, and revise contracts faster—without sacrificing precision. Boasting 3,400 law firms and in-house teams as customers, Spellbook is one of the most-used legal AI tools in the world.