Good Judgment, Bad Advice: Decision-Model Controllers Raise Agent Cost Without Improving Success

A study of a typed decision model, Jev 1.13, consulted only at deterministic decision points in a Claude Sonnet 5.5 terminal agent found the controller raised agent cost without improving task success, according to the research. The work examined whether delegating small stop, verify, or change-approach decisions to cheaper models makes agent scaffolds cheaper without degrading performance.

Agent scaffolds increasingly delegate small decisions whether to stop, verify, or change approach to cheaper models. We ask whether a typed decision model, Jev 1.13, consulted only at deterministic decision points, makes a Claude Sonnet 5.5 terminal agent cheaper without making it worse. In a pre-