📌Overview

Purpose: To provide a solution for managing console logging in MCP servers without disrupting protocol communication.

Overview: The MCP Server Logger is a package designed to enhance the logging experience for developers working with MCP servers using stdio transport. It prevents console.log messages from interfering with protocol communications by redirecting logs to a separate terminal.

Key Features:

• Patched Console Methods: Redirects console.log, console.warn, console.error, and console.debug outputs to a separate terminal, ensuring that MCP protocol communications remain uninterrupted.

• Easy Integration: Simple installation and setup within the MCP server code, allowing for quick adaptation with minimal code changes.

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MCP Server Logger

Console.log for your stdio MCP server

Why?

When developing an MCP (Model Context Protocol) server with stdio transport, console.log interferes with protocol communication.

For example, in MCP inspector (npx @modelcontextprotocol/inspector), calling console.log in your MCP server code causes:

Error from MCP server: SyntaxError: Unexpected token S in JSON at position 0

Solution

This package patches console methods (log, warn, error, debug) and redirects logs to a separate terminal.

Usage

Start the logger in a terminal where you want to see the logs:

npx mcps-logger

Install the logger in your MCP server:

npm install mcps-logger

Add it to your MCP server entry file:

import "mcps-logger/console";

Or use it in development mode only:

if (process.env.NODE_ENV !== "production") {
    import("mcps-logger/console");
}