[Xelynega]

That doesn't sound like the case for MCP though. It sounds like when implementing an MCP server there is a difference between the three transport methods that requires different code on the server.

This is a problem solved by other protocols that are just stacked on top of eachother without knowing how eachother work.

[skeledrew]

That depends on the library implementation. A given library can be anywhere on the spectrum from "user knowledge and management of the transport methods required" to "transport method is determined by protocol format or invocation" (eg. "local://..." vs "remote://...").