FastMCP Proxy not working after upgrading from 2.5.2 to 2.9+

[Aimankoli]

I've implemented a proxy server to act as an intermediary for connecting to multiple MCP servers via HTTP. My implementation uses FastMCP as the base class, and I successfully overrode the list_tools and call_tools methods while using earlier fastmcp versions.

The core logic involves retrieving a user's MCP configurations from MongoDB, instantiating them as MCPConfig objects, and then initializing Client objects to establish connections to these individual MCP servers. My application connects to this proxy server via a GoLang server, also utilizing an MCP Client object.

The Problem:

Upon upgrading to fastmcp version 2.9.0 or higher (specifically for its concurrent request handling improvements), my custom list_tools and call_tools methods are no longer being invoked. I've confirmed that ListToolsRequest objects are being sent to my proxy server through middleware logging, but the overridden methods themselves are not being called. This indicates a change in how fastmcp handles method dispatch or overriding in its newer versions.

Potential Causes I'm Considering:

Method Overriding Changes: It's possible that direct method overriding is no longer the intended or supported mechanism for custom logic in fastmcp 2.9+. Perhaps custom logic now needs to be implemented within middleware, even though initial attempts to do so didn't work.
ProxyClient Usage: Is it necessary to use a ProxyClient when connecting from my GoLang application to my fastmcp-based proxy, or when the proxy itself connects to other MCP servers?

[jlaupa]

Same for me.
we upgrade 2.8.1 to 2.9+ and claude say the responses is long...