Best AI for Contract Review: 8 Models Tested
A focused comparison of AI models for explaining a contract clause in plain English, with dates, renewal deadlines and responsible review.
Tested: September 2026
Key Takeaways
- The contract clause summary task is a narrow test of a supplier term, automatic renewal window and capped fee increase, not a general measure of intelligence. GPT-6 Astra leads thi
- The higher and lower examples below show the difference more clearly than a score alone. Read the answer against the brief, then read the review note for the constraint that change
- Use GPT-6 Astra as the first model to test for a supplier term, automatic renewal window and capped fee increase, then compare it with one other model on the exact source material
- This comparison is educational and is not legal advice. A business owner should ask qualified counsel to review the complete agreement, surrounding documents and commercial context
- Read the output against the original brief line by line. Check names, numbers, dates, owners and the requested format before improving the prose. A polished answer that changes one
- A single task cannot represent every workbook, meeting or agreement. The benchmark uses a fixed English brief, three runs and default reasoning settings, so it is evidence for a sh
The brief behind the score
The contract clause summary task is a narrow test of a supplier term, automatic renewal window and capped fee increase, not a general measure of intelligence. GPT-6 Astra leads this task at 100.0, but the details in the brief explain why the ranking matters to an operator.
Contract clause summary
Brief: Explain this supplier contract clause in plain English for the business owner: what it means, the exact dates or deadlines that matter, and what we must do to avoid being locked in. At most 150 words. Do not give legal advice beyond what the clause says and do not add terms that are not in the text.
Input: Clause 7. Term and renewal. This Agreement commences on 1 November 2026 and continues for an initial term of twenty four (24) months. Thereafter it renews automatically for successive twelve (12) month periods unless either party gives written notice of non renewal at least ninety (90) days before the end of the then current term. The Supplier may increase the Fees once per renewal period by no more than five percent (5%), on sixty (60) days written notice.
The point of this brief was not to reward a general essay. It asked for a particular format, a particular length and careful use of the supplied facts.
The best summaries preserve exact dates and distinguish the initial term from later renewal periods. They also avoid adding termination rights, penalties or other terms that are not in the supplied clause.
Two answers worth studying
The higher and lower examples below show the difference more clearly than a score alone. Read the answer against the brief, then read the review note for the constraint that changed the outcome.
| Example | Output and review |
|---|---|
| Higher-scoring example Claude Fable 5.1, run 3 | What it means: The contract runs for two years, then rolls over automatically for one year at a time unless one side cancels in writing. Key dates: - Start: 1 November 2026 - Initial term ends: 31 October 2028 - Non-renewal notice deadline: at least 90 days before the term ends - i.e. no later than 2 August 2028 (sending it earlier is safer) - If it renews, each new term ends 31 October the following year, with the same 90-day deadline (around 2 August each year) To avoid being locked in: Give the supplier *written* notice of non-renewal by the deadline. If you miss it, you're committed for another 12 months. Price: During each renewal period the supplier can raise fees once, by up to 5%, on 60 days' written notice. The clause doesn't say fees can rise during the initial term. Review note: Accurately covers the term, renewal mechanism, first notice deadline, required action and fee-increase limits in under 150 words without adding contractual terms. |
| Lower-scoring example Gemini 3.1 Pro, run 3 | What it means: The contract starts on November 1, 2026, and lasts for 24 months. After that, it automatically renews for 12-month periods. The supplier can increase your fees by up to 5% once per renewal period, but they must give you 60 days' written notice before doing so. Exact dates and deadlines: The initial term ends exactly 24 months after November 1, 2026. To stop the first automatic renewal, your deadline is 90 days before that 24-month term ends. For any future renewals, the deadline is 90 days before the current 12-month period ends. What you must do to avoid being locked in: You must provide the supplier with written notice that you are not renewing. This written notice must be given at least 90 days before the end of your current term. Review note: The answer accurately summarizes renewal and fee increases within 150 words, but omits the required 31 October 2028 end date and approximately 2 August 2028 notice deadline, leaving the owner to calculate them and repeating the notice requirement. |
A workflow for the result
Use GPT-6 Astra as the first model to test for a supplier term, automatic renewal window and capped fee increase, then compare it with one other model on the exact source material your team uses. Keep the prompt narrow, ask for the requested format and make the final review visible. We go deeper on this in our guide to the best AI for sales outreach and cold email.
In Krater, pick the model in the model picker and use Compare for a side by side check. Save the audience, format, source rules and approval standard in a Persona when the work repeats. The benchmark points to a starting model; it does not remove the need to inspect the actual output.
A clear boundary for contract work
This comparison is educational and is not legal advice. A business owner should ask qualified counsel to review the complete agreement, surrounding documents and commercial context before relying on a summary or making a contractual decision.
An AI summary can highlight dates, renewal windows and questions for counsel. It should not add rights, penalties or remedies that the supplied clause does not state.
What to check before you ship the answer
Read the output against the original brief line by line. Check names, numbers, dates, owners and the requested format before improving the prose. A polished answer that changes one of those details is less useful than a plain answer that preserves them.
Run one small test that would expose the likely mistake. Add a new spreadsheet row, read the action table against the transcript or compare every contract date with the clause. Keep the test result with the approved output.
When a source is incomplete, require the model to say what is missing. The reviewer should be able to tell the difference between a supplied fact, a reasonable interpretation and an open question.
Where the benchmark stops
A single task cannot represent every workbook, meeting or agreement. The benchmark uses a fixed English brief, three runs and default reasoning settings, so it is evidence for a shortlist rather than a promise about every business workflow.
The model still needs a source that is complete enough to review. Better prompting cannot repair a missing policy, an absent deadline or a clause that was copied without its definitions and schedules.
Use the result to choose what to test next. Keep the final decision with the person who owns the workbook, meeting, customer promise or contract review.
Turn the result into a team habit
A model comparison has lasting value when it becomes a review habit. Save the brief, the accepted answer and the correction that mattered. The next person can then start with the business rule instead of a blank prompt.
Use a Persona for recurring context and a Task for the review date. Keep the final source in the system that owns it, then use Krater to prepare the summary, question list or handoff around that source.
When the brief changes, rerun the comparison. A new policy, workbook layout or contract schedule can change which model is easiest to approve even when the benchmark score remains unchanged.
Make the reviewer visible
Name the person who approves the answer and the source they should use. A clear owner prevents a formula, action list or clause summary from circulating without anyone responsible for the final check.
Record the correction when the reviewer finds one. That note improves the next prompt and gives the team a practical example of the standard it expects.
The chart and the decision
The selected work covers contract clause summary. The chart is useful because it keeps the recommendation tied to those jobs instead of turning the overall ranking into a universal rule.
Use the winner as the first comparison, then check the runner-up on a real brief. A model that loses a few points may still be the better operational fit if it follows your house format with less editing.
A repeatable workflow
How to use this in Krater
The benchmark is a shortlist, not a reason to hand every job to one model. Pick a candidate in the model picker, then use Compare to run the same brief side by side. Look at the facts that survived, the format that came back and how much editing remains. Related reading: our guide to AI for HR and recruiting.
When the work repeats, create a Persona with the audience, house style, prohibited claims, approval rules and output format. Keep the source material in Keep and assign review work in Tasks. Krater provides 400+ models, so a team can keep one dependable choice for important work while testing another for a different format or turnaround. The next step is our guide to AI for marketing agencies.
Useful commands for this kind of work include /research, /summarize, /document, /image. Use them to organize source material, turn long notes into a brief, create a structured deliverable or prepare a visual direction. The operator still approves the final output.
Method and limits
The test covers 10 business tasks, 3 runs per model and a generation temperature of 0.7. The briefs cover Product description, Amazon listing bullets, Meta ad variants, Customer support reply, SEO title and meta description, Abandoned cart email sequence, Spreadsheet formula, Contract clause summary, Meeting notes to action items, Product photo prompt. Three independent judges were used: GPT-6 Astra, Claude Opus 5, Gemini 3.1 Pro. They did not see the name of the model they were reviewing, and a judge was left out when it came from the same company as that model. Each response was scored on 5 criteria from 1 to 5: correctness, brief, usefulness, clarity, ship_ready. The mean was rescaled to 0 to 100, then averaged across runs and tasks. For the workflow side of this, see our guide to AI spreadsheet generators.
This is a focused view of 1 task scores inside a 10-task comparison. AI judges, English prompts, one month and default reasoning settings all shape the result. Treat it as evidence for a shortlist, then test the briefs that matter to your team.
Frequently Asked Questions
Which model leads for contract clause explanations?
GPT-6 Astra leads this group at 100.0. That is a useful starting point, but your own facts and approval rules should decide the final choice.
Are these quality scores the same as usage popularity?
No. The scores come from controlled business briefs. Usage popularity is covered separately in the usage article.
Why can a high-scoring answer still need editing?
A response can follow the facts and still need a warmer tone, tighter format or a final brand review.
How do I stop a model inventing product details?
State what the source does not say, require source-only claims and check every named feature before publishing.
How can I compare models on my own work?
Pick two models in Krater, run the same brief in Compare and save the approved instructions in a Persona.
How many models are available in Krater?
Krater provides 400+ models across text, research, image, video, voice and other workflows.
The Bottom Line
For contract clause explanations, start with GPT-6 Astra, compare it with Claude Opus 5 and keep the source facts visible through review. The best choice is the one your team can approve and ship without risky additions.