Claude’s Protein Design Hit Rate Was 26.8%. One Target Returned 0 for 90.

Author(s): Decoding AI Originally published on Towards AI. We refit Anthropic’s published per-target protein design counts on Aug 25, 2026. Ninety designs went into the wet lab against maltose-binding protein. Ninety came back with nothing. That is the part of the story that stopped us. On August 18, 2026, Anthropic published the results of an autonomous protein design campaign, and the number everyone repeated was the Claude protein design hit rate: 354 binders out of 1,320 designs, 26.8%, against an industry norm of 10–15%. It is a real result, independently validated in two contract labs. But sitting inside that 26.8% is a target where the agent produced ninety designs, every one of which was synthesized, expressed, and measured — and not one of them bound. Both facts came out of the same campaign, the same prompt, the same model. So we spent August 25 doing the arithmetic nobody in the coverage did: 26.8% is a portfolio average across sixteen targets, not the probability that your target works. Run the published per-target counts through a binomial test and a single shared hit rate is rejected at p ≈ 1.8 × 10⁻⁶³. Fit a model that allows targets to differ and the picture invert…

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