URSA Reaction Plausibility: leaderboard
Metric: Accuracy (%; binary plausible or implausible verdicts on the 1,000 expert-labeled reactions of URSA-reaction-plausibility-bench-2026, 500 plausible and 500 implausible, collected from synthesis-planner outputs; default reasoning effort; higher is better). Source: arxiv.org. Saturation forecast: Around December 2026. 4 models tracked.
Top models
| # | Model | Score |
|---|---|---|
| 1 | Gemini 3.1 Pro (Preview) | 83 |
| 2 | GPT-5.5 | 76 |
| 3 | Grok 4.3 | 75 |
| 4 | Claude Opus 4.8 | 73 |
Interactive version: theaggregate.ai/benchmark?slug=ursa-reaction-plausibility · How It Works · Data refreshed daily, snapshot 2026-09-29.