pguso

pguso / mcp-from-scratch

Public

Learn Model Context Protocol (MCP) from scratch in plain Node.js. Build a working MCP server step by step with zero black boxes, from JSON-RPC and stdio transport to tools, prompts, resources, sampling, and agent workflows.

ai ai-agents json-rpc learning llm
12
4
89% credibility
Found May 26, 2026 at 12 stars -- GitGems finds repos before they trend. Get early access to the next one.
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AI Analysis
JavaScript
AI Summary

A hands-on educational repository that teaches the Model Context Protocol from absolute zero by building a working MCP server step-by-step in plain Node.js, culminating in a server that connects to Claude Desktop or AI agent workflows.

How It Works

1
💡 You discover MCP exists

You hear about a new way to connect AI assistants to tools and data, and you want to understand how it actually works under the hood.

2
📦 You download the learning kit

You find a repository that promises to teach you everything from scratch—no shortcuts, no mysterious code you just copy and paste.

3
📖 You read the first lesson

You learn that MCP is like a universal charger for AI tools—just as USB standardized how devices connect, MCP standardizes how AI apps talk to tools.

4
🔨 You build piece by piece

Following clear instructions, you create the message format, connect two programs together, and complete a handshake that lets them talk.

5
🎉 Your tools work in Claude Desktop

The moment everything clicks: you call your own tool from a real AI assistant and it responds. You built this yourself, and you understand every line.

6
🌟 You add more features

You add read-only data sources, reusable prompt templates, and notifications that push updates automatically when things change.

🚀 You have a working MCP server you truly understand

You've gone from zero knowledge to a complete, working MCP server—and you could explain every part of it to someone else.

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Star Growth

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AI-Generated Review

What is mcp-from-scratch?

This is a hands-on learning path for the Model Context Protocol (MCP) built entirely in plain Node.js. Instead of installing an SDK and calling it done, you build a working MCP server from the ground up--starting with raw JSON-RPC messages, then stdio transport, then the full protocol handshake, tools, resources, prompts, notifications, and sampling. By the end, your server connects to Claude Desktop or any MCP-compatible host without modification. The approach is explicitly anti-framework: no npm dependencies in the core modules, no magic abstractions, every decision explained in comments.

Why is it gaining traction?

The MCP ecosystem is young, and most tutorials hand you a TypeScript SDK before explaining why the protocol works the way it does. This repo flips that--it starts with the wire format and builds up. The hook is "zero black boxes": if you finish all twelve modules, you understand what every MCP SDK does internally because you implemented it yourself. The progressive structure (each module assumes you ran the previous one) makes the learning concrete rather than theoretical.

Who should use this?

Backend or full-stack developers building MCP servers who want to understand the protocol deeply before relying on a framework. Developers integrating AI tools into applications and debugging MCP connections. Anyone curious how Claude Desktop or Cursor actually communicates with tool servers. Not ideal for developers who just want to ship a working server fast--the SDK path is faster there. Ideal for developers who want to understand the "why" behind the protocol.

Verdict

The credibility score of 0.8999999761581421% reflects a very new repo with only 12 stars, so treat it as educational material rather than production-ready infrastructure. That said, the documentation is thorough, the progression is well-designed, and the no-dependency constraint forces genuine understanding. If you're serious about MCP, this is the learning path that actually teaches you the protocol instead of hiding it.

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