add client kwargs to proxy clients and meta to proxy tool calls (#2520)

* add client kwargs to proxy clients and meta to proxy tool calls

* Update src/fastmcp/client/transports.py

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Update src/fastmcp/server/proxy.py

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Update src/fastmcp/utilities/mcp_config.py

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* update formats and fix lint errors

* remove client callback passthrough

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Author: cegersdoerfer

src/fastmcp/server/proxy.py

@@ -287,9 +287,16 @@ async def run(
     ) -> ToolResult:
         """Executes the tool by making a call through the client."""
         async with self._client:
+            context = get_context()
+            # try to get request context meta
+            meta = (
+                dict(context.request_context.meta)
+                if hasattr(context, "request_context")
+                and hasattr(context.request_context, "meta")
+                else None
+            )
             result = await self._client.call_tool_mcp(
-                name=self.name,
-                arguments=arguments,
+                name=self.name, arguments=arguments, meta=meta
             )
         if result.isError:
             raise ToolError(cast(mcp.types.TextContent, result.content[0]).text)

src/fastmcp/utilities/mcp_config.py

@@ -43,8 +43,7 @@ def mcp_server_type_to_servers_and_transports(
 
     if isinstance(mcp_server, TransformingRemoteMCPServer | TransformingStdioMCPServer):
         server, transport = mcp_server._to_server_and_underlying_transport(
-            server_name=server_name,
-            client_name=client_name,
+            server_name=server_name, client_name=client_name
         )
     else:
         transport = mcp_server.to_transport()