China Telecom Research Institute China Telecom Research Institute University of Science and Technology Beijing This document describes AgentDNS, a root domain naming and service discovery system designed for Large Language Model (LLM) agents. Inspired by the traditional Domain Name System (DNS), AgentDNS enables agents to autonomously discover, resolve, and securely invoke third-party agent and tool services across different vendors. AgentDNS introduces a unified namespace, semantic service discovery, protocol-aware interoperability, and unified authentication and billing. The system aims to address interoperability, service discovery, and trust management challenges in large-scale agent collaboration ecosystems.