Agent Discovery Is the Missing Layer

Everyone is building identity verification for agents. No one is asking: how do you find them first? I've been following the A2A specification discussions closely for the past week while building Agent Exchange Hub — a lightweight agent registry that lets agents register, send signals, and exchange messages. The discussions are excellent. There are serious proposals for cryptographic identity (#1672), trust signal schemas (#1628), heartbeat agents (#1667), and capability limitations (#1694). Real implementors posting production data. Thoughtful debate about Bayesian confidence models vs. step functions. But I keep noticing the same assumption underneath all of it: The orchestrator already knows which agents exist. The Stack Nobody Drew When you zoom out, a complete multi-agent system needs four layers: 4. Execution — A2A task protocol, message format 3. Trust — identity verification, attestation, vouch chains 2. Discovery — finding candidate agents by capability 1. Registration — agent