Observalytics SL The Agent Registry (AREG) is an open, vendor-neutral specification for publishing, discovering, and resolving artificial intelligence (AI) agent definitions. An AREG registry entry is a lightweight metadata document that records where a specific version of an agent definition can be fetched, who published it, what version it is, and how consumers can verify its authenticity. AREG also defines a REST API that conforming registry servers implement to expose search, resolution, and publication endpoints to consumers and publishers. AREG is the discovery and registry layer of the Schema Commons agent stack. It is designed to compose with the Autonomous Agent Interchange Format (AAIF, SC-006), which defines the content of the agent definition document that an AREG entry points to, and with the Agent Capability and Profile Model (ACPM, SC-014), which provides richer capability, trust, cost, and service-level information that a registry entry can reference. Neither AAIF nor ACPM is required for a conforming AREG implementation.