yes, that's basically the shape of it, a capability proxy that only hands out the exact authority needed for the next step, then refuses replay or privilege creep. the bit people used before was mostly trust the framework, or stick a coarse api key / token in the agent and hope prompt boundaries kept the pieces apart, which is where these multi-agent setups get ugly fast. what this paper is poking at is the same old delegation problem we keep seeing in bridges and auth middleware, once one agent can act for another, you need some runtime that can say "not that action, not again, and not outside this context." microseconds matters because if the broker is slower than the model call chain, everyone will just bypass it, or quietly reintroduce the trust leak elsewhere.