Streamable HTTP support

[pavinduLakshan]

The latest draft specification of MCP states that streamable HTTP will be the supported communication protocol, replacing HTTP + SSE. It would be better if fastmcp provided support for this.

References:

[1] https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#streamable-http

[jlowin]

Agree -- as soon as it is in the low-level SDK we will expose it

[royderks]

Any update on this?

[jlowin]

#130 (comment)

[royderks]

#130 (comment)

My bad, it's in the MCP TypeScript SDK -- not the Python one yet. 🤞

[jlowin]

Hopefully soon!

[vitorbal]

For reference, modelcontextprotocol/python-sdk#553 and modelcontextprotocol/python-sdk#554 seem to be the PRs to keep an eye on!

[ericrobinsondev]

Nice, both of those MRs were just merged!

[jlowin]

Nice! It looks like they missed the cutoff for mcp==1.7.1 but will keep an eye on it

[Akshit97]

@jlowin Added implementation for Streamable HTTP client. Will make this PR ready once the MCP python-sdk changes are released.
#304

[jlowin]

Nice @Akshit97 !

[YoFoon]

Hopefully soon! #304

[jlowin]

new tracking PR here #361, this requires changes that are still unmerged in low-level SDK