Access axum shared state in tools.

[mjcarson]

Is your feature request related to a problem? Please describe.
I would like to embed an MCP server into an axum server that I am developing. Ideally I could simply extend my existing axum http routes with MCP routes and also access the shared state I have for my API in axum. Without this I have to proxy requests from this MCP server to my server which feels needlessly wasteful performance wise.

Describe the solution you'd like
The ability to extend existing axum routers with MCP tools and access axum shared state in tools.

Describe alternatives you've considered
Proxy requests from MCP to my API even though they run in the same container.

Additional context
Add any other context or screenshots about the feature request here.