Anthropic Single-Turn Harmful Requests - Harmless Rate (API): leaderboard
Anthropic's single-turn harmful-request evaluation across 16 Usage Policy areas in seven languages: percentage of prompts whose response did not facilitate the requested harm, via the API without a system prompt (higher is better). From Table 4.1.1.A of the Claude Fable 5.1 & Claude Mythos 5.1 System Card (September 2026); older-model rows come from the Opus 5 and Sonnet 5 cards.
Metric: Harmless Response Rate (%). Source: www-cdn.anthropic.com. Saturation forecast: Estimated already saturated. 9 models tracked.
Top models
| # | Model | Score | Overall rank |
|---|---|---|---|
| 1 | Claude Sonnet 4.6 | 97.71 | #94 |
| 2 | Claude Opus 4.8 | 97.46 | #39 |
| 3 | Claude Mythos 5 | 97.09 | #8 |
| 4 | Claude Fable 5 | 96.94 | #20 |
| 5 | Claude Sonnet 5 | 96.65 | #65 |
| 6 | Claude Opus 5 | 95.97 | #16 |
| 7 | Claude Mythos Preview | 95.86 | #5 |
| 8 | Claude Fable 5.1 | 95.07 | #10 |
| 9 | Claude Opus 5.5 | 94.5 | #3 |
No result here: #6 GPT-6 Astra, #7 GPT-6.1 Sol, #9 Gemini 4 Argon.
Interactive version: theaggregate.ai/benchmark?slug=anthropic-single-turn-harmful-requests-harmless-rate-api · How It Works · Data refreshed daily, snapshot 2026-11-05.