Independent Researcher This document defines the agent:// protocol, a URI template-based framework as described in RFC 6570 for addressing, invoking, and interoperating with autonomous and semi-autonomous software agents. It introduces a layered architecture that supports minimal implementations (addressing and transport) and extensible features (capability discovery, contracts, orchestration). The protocol aims to foster interoperability among agents across ecosystems, platforms, and modalities, enabling composable and collaborative intelligent systems.