The proliferation of custom tool interfaces has fragmented the agent ecosystem. Anthropic’s open-sourced Model Context Protocol (MCP) establishes a universal, vendor-neutral standard for connecting AI clients with real-world enterprise data systems, tools, and prompts. This guide details the protocol wire specifications and walks through building a production-grade MCP server.
01 The Wire Protocol: JSON-RPC 2.0 & Transports
MCP is built atop the battle-tested JSON-RPC 2.0 specification, supporting two primary transport mechanisms:
- stdio (Standard Input/Output): The host process (e.g., Claude Desktop, Cursor) spawns the MCP server as a local child process, communicating over stdin/stdout. Ideal for local desktop tooling;
- SSE (Server-Sent Events) over HTTP: Asynchronous full-duplex communication suitable for remote microservices and shared corporate knowledge bridges.