I think that comparing MCP to LSP servers is the most apt. They both function to connect one software application to another for the sake of increased functionality and less errors.

You might use a LSP to determine whether or not your code is syntactically correct. Similarly, MCPs can allow a program to determine whether or not a partulicular DOM node renders in a browser or even control local programs like Blender or Photoshop.

I might describe MCP as something like a framework for developing programs analogous to LSPs.