What exactly is an MCP server and what does it do?

An MCP server provides access to data or functionality implemented by some outside service. It acts as a specialized interface that exposes tools, prompts, and resources in a standardized way. In a GitHub example, the MCP server for GitHub would contain tools like get repositories, and it would connect directly to GitHub's API behind the scenes. Your application server communicates with the MCP server, and the MCP server handles all the GitHub-specific implementation details. This separation means service providers can ship one official MCP implementation, and many different applications can immediately benefit without each one re-implementing the same integration.