How to Combine MCP and A2A in One Enterprise Agent Architecture

This article presents an enterprise reference pattern for combining MCP (Model Context Protocol) and A2A (Agent-to-Agent) protocols in a single agent architecture. It clarifies that MCP standardizes agent-to-tool connectivity—discovery, invocation, and schema validation—while A2A handles agent-to-agent collaboration, including task delegation, message exchange, long-running task management, and artifact return. The key design principle is not choosing one protocol over the other but defining clear boundaries: use A2A across agent boundaries and MCP inside each agent's execution boundary. The article also covers identity propagation, discovery, gateways, policy enforcement, approval controls, and observability, ensuring agents collaborate without exposing internal tools and tools remain governed without being misrepresented as autonomous agents.