MCP + A2A: The Two-Protocol Stack That Will Define Agent Ecosystems in 2025

MCP + A2A: The Two-Protocol Stack That Will Define Agent Ecosystems in 2025 Anthropic donated MCP to the Linux Foundation in December 2025. Google contributed A2A to the Linux Foundation in June 2025. Over 150 organizations now support the A2A protocol. These aren't just press releases — they're the birth of a new infrastructure layer for AI. What Each Protocol Does MCP (Model Context Protocol) is vertical. It connects a single agent to external tools, data sources, and services. Think of it as a universal toolbelt — the "USB-C for AI" that solves the N×M integration problem. Without MCP, every agent needs custom connectors for every data source. With MCP, one connector works across all compatible systems. A2A (Agent-to-Agent Protocol) is horizontal. It connects independent agents to each other. Agents advertise capabilities via "Agent Cards," discover each other, and collaborate on tasks that exceed any single agent's capability. This is what turns isolated agents into ecosystems. Why