Are you trying to say that REST APIs don't have a strict wire format with shared semantics for a huge range of features?
Isn’t that the case? Aren’t REST people still debating about what makes a true beautiful REST API?
The wire format certainly isn’t strict
Kind of--I'm saying that RESTful APIs are just an abstract vocabulary to describe state transfer operations, whereas MCP describes a concrete set of such operations. REST sits on top of the HTTP protocol layer, MCP sits on top of REST (if we accept how the meaning of REST has been butchered, but you know what I mean.)
This is easy to see when you think in terms of a client: It is pretty much impossible to build an opinionated UI for any kind of RESTful API, while creating one for an MCP server is fairly self-explanatory: MCP servers offer a mandatory and complete runtime introspection endpoint (you can retrieve a listing of available tools/resources/prompts etc. along with their parameter and return type schemas). So that means clients have a way to exhaustively describe everything an MCP server is able to do with a vocabulary that carries over exactly to other servers - a tool is a tool everywhere.