Building an MCP server from a REST API

This practical guide details the process of building an MCP server that wraps an existing REST API, using a fictional service called Pantry as an example. The guide focuses on exposing a curated subset of REST API endpoints to an LLM agent through tools, resources, and prompts, with an emphasis on design decisions, such as which endpoints to expose and how to structure them. It covers project setup using Python with FastMCP, error handling strategies, and implementing OAuth-based authentication using AuthKit to secure the server. The guide emphasizes writing tool descriptions that are clear for the model, structuring returns with useful summaries, and using the MCP Inspector for testing. It provides best practices for integrating with clients and troubleshooting common issues, aiming to create a scalable and maintainable server that effectively serves user intents.