What Is MCP (Model Context Protocol)? A Beginner's Guide

6 min readUpdated October 29, 2026

The Model Context Protocol (MCP) is an open standard, introduced by Anthropic in November 2024 and since adopted across the industry, for connecting AI applications to external tools and data. Think of it as a universal adapter: build an integration once as an MCP server, and any MCP-compatible app can use it.

The pieces

Host: the AI application (a chat app, an IDE, an agent).
Client: lives inside the host and holds a connection to each server.
Server: exposes capabilities to the host:
- Tools: functions the model can call
- Resources: data the app can read into context
- Prompts: reusable prompt templates

Messages use JSON-RPC 2.0. Local servers typically talk over stdio. Remote servers use HTTP (Streamable HTTP).

Why it matters

Before MCP, every AI app needed custom glue code for every integration. With MCP, a company can wrap its API once and make it usable from many assistants and agents. For AI engineers, MCP servers are becoming a standard way to expose internal systems safely.

Security considerations

An MCP server runs code and returns text that ends up in the model's context. Treat servers like any dependency with credentials: review them, scope permissions tightly, require confirmation for destructive tools, and be aware that tool output can carry prompt injections.

Build your first server

The official SDKs (Python, TypeScript and others) let you declare tools with a decorator and a docstring, and run the server over stdio in a few lines. Our MCP lesson includes a working Python template you can copy.

Practice what you just read

▶Practice it hands-onMCP: Model Context Protocol ▶Practice it hands-onTool Use (Function Calling)▶Practice it hands-onThe Agent Loop

Frequently asked questions

Is MCP only for Claude?

No. It's an open protocol with SDKs in several languages, supported by many AI applications and developer tools.

What's the difference between MCP and function calling?

Function calling is how a model requests a tool inside one API call. MCP is a standard for packaging and connecting tools and data across applications.