Zero-Configuration Agent Discovery (draft-jakab-dawn-agent-discovery-mdns-01)

Abstract

Protocols for communication between autonomous software agents typically discover agents through documents retrieved over HTTPS from a well-known URI. This model requires a discovering party to already know an agent's host name or URL, or to consult a centralized catalog. It provides no zero-configuration mechanism for enumerating agents that are present on a local network. This document describes how existing, widely deployed protocols, Multicast DNS (mDNS) and DNS-Based Service Discovery (DNS-SD), can be used to advertise and discover agents on a local link, with no new protocol machinery. It presents a general, protocol-independent two-stage discovery model in which lightweight enumeration over DNS-SD is followed by obtaining full agent metadata over the agent's native transport, whether by retrieving a description document or by connecting to the agent and performing its native handshake. The DNS-SD records carry a small set of discovery parameters that is shared with agent discovery in unicast DNS. The document gives worked instantiations of that model for the Agent2Agent (A2A) protocol and the Model Context Protocol (MCP).