mcp-echo-server

Provides a minimal template for bootstrapping an MCP (Model Context Protocol) server with standard lifecycle hooks. Implements the MCP server specification by exposing initialization, request handling, and shutdown patterns through a Node.js-based server that listens for MCP protocol messages over stdio or network transport. The template establishes the foundational server structure needed to respond to client connections and route incoming MCP requests to appropriate handlers.

Implements a basic message echo mechanism that receives MCP protocol requests and returns them as responses, demonstrating the request-response cycle without business logic. Routes incoming messages through a handler that parses the MCP JSON-RPC format, identifies the message type (tool call, resource request, etc.), and echoes the content back to the client. This pattern establishes the foundation for replacing the echo logic with actual tool implementations or resource handlers.

Ensures outgoing responses conform to the MCP protocol specification by structuring messages as valid JSON-RPC 2.0 objects with required fields (id, jsonrpc version, result/error). The server validates that responses include proper message envelopes before transmission to clients. This capability guarantees that even a minimal echo server produces protocol-compliant output that MCP clients can parse and process without errors.

Establishes bidirectional communication with MCP clients using standard input/output streams (stdin/stdout), allowing the server to receive messages on stdin and transmit responses on stdout. This transport mechanism is the standard for MCP servers running as child processes, enabling integration with desktop applications like Claude that spawn MCP servers as subprocesses. The implementation handles line-delimited JSON message parsing and serialization for reliable stdio-based communication.

Manages the server lifecycle including process initialization, signal handling for graceful shutdown, and cleanup of resources. The template implements basic process event handlers (SIGINT, SIGTERM) to ensure the server terminates cleanly when signaled by the parent process. This capability ensures the server can be reliably started and stopped by MCP clients without leaving orphaned processes or resource leaks.