A hands-on, low-level understanding of MCP using command-line tools

I like to understand what’s happening behind the scenes with any technology, especially when a tool or protocol is usually introduced through prebuilt clients. In this tutorial we will use tools commonly found on Linux systems to send MCP requests ourselves, and see how a few of its features work. The focus will be on understanding the protocol, transports, and authentication at a low level, and gaining an insight into how MCP clients and servers communicate under the hood. Setup Start by creating a folder for the tutorial, then a virtual environment with some dependencies that will be needed: mkdir -p tutorial_mcp_low_level cd tutorial_mcp_low_level uv init uv sync uv add fastmcp source .venv/bin/activate Create a server.py with a minimal MCP server setup. from fastmcp import FastMCP mcp = FastMCP("learn") @mcp.tool() def add(a: int, b: int) -> int: """Add two integers together!""" return a + b This is a bare-bones MCP server with a single registered tool: add, which adds two…

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