Support for HTTP MCP servers

[vidarian]

Most MCP servers are implemented as remote http servers and continue to do so. There doesn't seem to be support for this in zed but considering there's already support for stdio mcp servers adding http support should be trivial.

[pimeys]

We're developing an MCP gateway internally, and it would be really cool if I didn't need to use cursor every time I want to test the server.

Zed seems to only support stdio for MCP communication, but it would be great to have streamable HTTP support for remote MCP services. Yeah, this does require implementing oauth which takes a bit of effort (tell me about it), but eventually it would enable us to use zed instead of cursor for local testing.

There's an ok crate for this: rmcp, which is not awesome but does its job.

[vidarian]

rmcp is the official mcp library for rust, so even if it's not amazing I think still should be adopted by zed since as already apparent maintaining their own implementation and having parity with the spec is not happening.