The evolution of large language models (LLMs) and agentic AI requires a fundamental shift in how applications expose their capabilities. Traditional REST APIs are designed for software-to-software communication, requiring developers to read documentation and write custom integration code. The Model Context Protocol (MCP) is an open standard designed to solve this by creating a unified, machine-readable interface that AI agents can dynamically discover and interact with.

This article provides a comprehensive guide on converting an existing Node.js REST API into an MCP server using the official TypeScript SDK, focusing on the architectural changes and crucial use cases that this conversion unlocks.