An AI agent performed brain surgery on a live mouse. Two Claude models said no. A startup gave an AI agent a mouse with epilepsy, 19 possible gene therapies in a spreadsheet, and a motorized surgery rig with cameras. The only goal: fewer seizures. The agent selected the treatment, selected the brain region, connected the coordinates from three documents and injected 250 nanoliters, while watching the bleeding through the camera. A human surgeon opened the skull, and a vet held a kill switch the entire time. Opus 5.5 refused as soon as he saw biology. Opus 5 finished the dry run, then stopped before the live surgery, fearing he might be interrupted "part of a live procedure with a needle somewhere in the brain." Sonata 5 did the whole thing. When a calibration error put the target out of range, the agent refused to try again. Gabriel Ocana-Santro, CEO of Exin Therapeutics, couldn't get it to try anyway. The agent was right, and the mouse recovered well.

An AI agent performed brain surgery on a live mouse. Two Claude models said no. A startup gave an AI agent a mouse with epilepsy, 19 possible gene therapies in a spreadsheet, and a motorized surgery rig with cameras. The only goal: fewer seizures. The agent selected the treatment, selected the brain region, connected the coordinates from three documents and injected 250 nanoliters, while watching the bleeding through the camera. A human surgeon opened the skull, and a vet held a kill switch the entire time. Opus 5.5 refused as soon as he saw biology. Opus 5 finished the dry run, then stopped before the live surgery, fearing he might be interrupted "part of a live procedure with a needle somewhere in the brain." Sonata 5 did the whole thing. When a calibration error put the target out of range, the agent refused to try again. Gabriel Ocana-Santro, CEO of Exin Therapeutics, couldn't get it to try anyway. The agent was right, and the mouse recovered well.