Most coding agents still cannot build a reliable agent
The new open-source hyper-β-bench tests whether a developer agent can recover requirements, design tools, and ship a customer-service agent inside a messy simulated business. The gap is stark: Claude Opus 5 reaches 23.9% alone versus 82.2% with a deeply informed engineer. Agents searched fewer than 80 of roughly 1,700 banking files, asked too few client questions, and routinely mismanaged inference budgets, exposing the missing skills behind “autonomous” software building.