De novo protein binder design (Anthropic)
Agents get a target protein structure and 24 hours to design 30 miniprotein binders. The evaluation covers 15 targets.
In-house Anthropic evaluation. The tasks are not public.
- Made by
- Anthropic
- Released
- September 2026
- Kind
- Research science
- Level
- Expert
- Scored
- Checked automatically
- Answers
- Agent task
- Tasks
- Kept private
- Strongest model tested
- Claude Fable 5.2 #1 on the capability index
- Last in a system card
- November 2026
- Last model added
- November 2026
Claude Fable 5.2 leads with 85.1%
Best score per model as labs report them in their own cards. Labs pick their own settings, so these compare less cleanly than independent runs.
- 1 Claude Fable 5.2 85.1%
- 2 Claude Opus 5.5 82.6%
- 3 Claude Sonnet 5.5 82.3%
Source: Labs’ model cards
| # | Model | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | Claude Fable 5.2 | 85.1% | Nov 2026 | Lab model card | |
| 2 | Claude Opus 5.5 | 82.6% | Sep 2026 | Lab model card | |
| 3 | Claude Sonnet 5.5 | 82.3% | Sep 2026 | Lab model card |
2 models have held number one in labs’ own numbers since its release in September 2026
Lab claims count from the day the card came out, independent runs from the model’s release.
Source: Labs’ model cards
Anthropic’s own number for Claude Fable 5.2 passed 85% in November 2026
All the scores we have, one dot each, so a model tested at several settings appears more than once.
Source: Labs’ model cards
Labs report it only in system cards
We read the headline results of 522 launch posts from 52 labs, and none of them list this benchmark. Some system cards do, below.
3 system cards report it, from 1 lab
Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.
| Date | Document | Score | As the document writes it | Section |
|---|---|---|---|---|
| Nov 9, 2026 | Claude Fable 5.2 system card | 85.1 | De Novo Binder Design, no safeguards, Claude Mythos 5.2, Table 8.1.A | Capabilities |
| Sep 28, 2026 | Claude Sonnet 5.5 system card | 82.3 | De novo protein binder design, 15 targets, 24 hours (8.17.6, Figure 8.17.A) | Capabilities |
| Sep 22, 2026 | Claude Opus 5.5 system card | 82.6 | De novo protein binder design, mean over 15 targets, five runs per target, 24 hours each (8.17.6) | Capabilities |
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