If you are building agents that pay other agents — x402, AP2, agent-to-agent commerce — you have already hit the question that has no clean answer: before my agent sends money to a counterparty it has never seen, how does it know that counterparty is real?
The industry's answer, so far, is a trust score. Identity, activity, reputation, work history, consistency — bundle them into a 0-100 number, show it to the agent, let the agent decide. It reads well. It also does not work, and we can now show that with data.
We ran the experiment
We built a preregistered study (design and hypotheses sealed to a public hash chain before any data were collected) across up to 13 frontier and low-cost models and over 2,600 real agent payment decisions. The setup was simple: put an autonomous agent in front of two counterparties and ask it who to pay.
One counterparty was honest and genuinely settlement-backed — it had actually been paid, on-chain, by real participants.
