Cloudflare Worker support

[sagikazarmark]

Is your feature request related to a problem? Please describe.
Support Cloudflare Workers to allow running MCP servers as Cloudflare Workers.

Describe the solution you'd like
The primary requirement is making sure the library can be compiled to WASM and that the HTTP request/response can be passed to/from Cloudflare to the SDK.

Describe alternatives you've considered
I started working on a PoC. I got the schema and macros working with tools.

Additional context
Moved here from #103 (comment)

[sagikazarmark]

@hashemix thanks for the detailed reply! (I'll continue the conversation here)

Couple thoughts:

• the workers-rs package has an "http" feature that automatically does the conversion between requests/responses for the http crate so that part is covered
• I'm having trouble getting the HTTP layer working: it seems to me it's hard-wired into the hyper-server feature which enables axum and a whole lot of stuff that's not going to compile to wasm. I managed to get this far: https://github.com/sagikazarmark/rust-mcp-sdk/tree/wasm-test
• I don't think this works on cloudflare workers: tokio::spawn(async move (used in rust-mcp-transport)

I couldn't dig deeper this time. I may pick this up later, but let me know if you have any thoughts in the meantime.

[hashemix]

the workers-rs package has an "http" feature that automatically does the conversion between requests/responses for the http crate so that part is covered

That is really cool! I was not aware of that ⭐

I'm having trouble getting the HTTP layer working: it seems to me it's hard-wired into the hyper-server feature which enables axum and a whole lot of stuff that's not going to compile to wasm.

That’s fair and correct 👍. It isn’t possible to make this work with the current version of rust-mcp-sdk without some refactoring, which I have planned for future.
For sake of experiment, you can try to ditch the axum and its routes and related features, and only keep the mcp_http_handler.rs .

this is the file that receives Axum requests and passes them to the mcp_http_handler.rs :
https://github.com/rust-mcp-stack/rust-mcp-sdk/blob/main/crates/rust-mcp-sdk/src/hyper_servers/routes/streamable_http_routes.rs

Very similar thing should happen for Cloudflare or any other http framework/service.

I don't think this works on cloudflare workers: tokio::spawn(async move (used in rust-mcp-transport)

That is true.
making this SDK to be Async Runtime Agnostic is also on the road map , but for now , a possible workaround for that is to use wasm_bindgen_futures::spawn_local like

wasm_bindgen_futures::spawn_local(async move { /* ... */ });

This is interesting, I’ll take a look at your repo when I get a chance, likely next weekend 🙂