China Telecom China Telecom The large-scale deployment of autonomous AI Agents introduces challenges to capability description, registration, and discovery. Existing agent communication protocols mainly focus on application- layer interactions and typically rely on centralized registration and discovery mechanisms, which limit scalability, robustness, and semantic extensibility. This document proposes a distributed and hierarchical capability registration and information synchronization mechanism for AI Agents. The mechanism introduces a multi-level capability taxonomy, capability vectors, and globally unique Service Identifiers (Service IDs), and defines two functional entities: Agent Capability Registration Server (ACRS) and Agent Capability Access Server (ACAS). A capability table is constructed and synchronized among ACRSs to enable semantic-based forwarding of capability-related requests. Furthermore, capability registration and discovery procedure are specified, enabling precise selection of agents based on task requirements. The proposed mechanism provides a scalable foundation for capability-aware routing and semantic collaboration in the Internet of Agents (IoA).