MCP: How To Build Custom SSE Server and Client | Full Deep Dive Tutorial

In this video, we’re building a Custom MCP (Model Context Protocol) Client and Server from scratch using Starlette, SSE (Server-Sent Events) transport, and JSON-RPC. If you’ve ever wondered how LangChain, OpenAI tools, or AI agents communicate over live connections — this is the video for you. We’ll walk through: How to implement an SSE transport layer for real-time bidirectional communication. How the MCP server uses in-streams and out-streams for JSON-RPC messaging. Creating custom routes for /sse and /messages/. How MCP streams work internally with ASGI, Starlette, and Python async. By the end, you'll have a working custom client and server fully compatible with the MCP spec.