Futurewei China Telcom Emiliaprotocol AI Huawei This document examines deployment scenarios for AI agent collaboration and analyzes the circumstances under which AI Agent Gateway functions provide operational or interoperability benefits that cannot be achieved through direct agent-to-agent communication alone. The document considers both single-domain and multi-domain deployments, identifies specific challenges associated with each deployment model, evaluates the limitations of existing agent communication mechanisms (including MCP and A2A) with respect to those challenges, and demonstrates that gateway functions are necessary in deployments involving multiple tenants, multiple vendors, or multiple administrative domains.