MCP Transport

MCP defines two transport mechanisms for communication between clients and servers: stdio (standard input/output) for local processes and SSE (Server-Sent Events) over HTTP for remote servers. The transport layer determines how MCP messages are serialized and delivered, using JSON-RPC 2.0 as the message format for both transports. Stdio transport runs the MCP server as a child process of the client, making it ideal for IDE integrations and local tools where latency and reliability are paramount, while SSE transport enables connecting to remote servers over the network for cloud-hosted integrations. Understanding the transport layer matters because it constrains your deployment architecture — a stdio-based server can't be shared across multiple clients simultaneously, while an SSE server introduces network latency and authentication complexity. This concept connects to MCP overview for the protocol fundamentals, MCP server primitives for what capabilities travel over the transport, and MCP security for the authentication and authorization concerns in remote transports.