Model Context Protocol (MCP) vs. Agent2Agent (A2A): which protocol do you need?

What Is AI Agent Tool Calling? MCP, Function Calling, and A2A Explained (2026)

ToolBench evaluated 219,444 tools across 43,467 MCP servers, confirming that LLM-to-system protocol connectivity is largely solved. Scaling production multi-user agents now depends on tool quality: context efficiency, delegated authorization, audits, and intent-optimized design—not protocol improvements.