Small updates from PR feedback

src/fastmcp/client/transports.py

@@ -879,7 +879,7 @@ class MCPConfigTransport(ClientTransport):
         # if there's exactly one server, create a client for that server
         elif len(self.config.mcpServers) == 1:
             self.transport = list(self.config.mcpServers.values())[0].to_transport()
-            self._underlying_transport = self.transport
+            self._underlying_transports.append(self.transport)
 
         # otherwise create a composite client
         else:

src/fastmcp/mcp_config.py

@@ -90,10 +90,10 @@ class _TransformingMCPServerMixin(FastMCPBaseModel):
         description="The tags to exclude in the proxy.",
     )
 
-    def _to_server_and_transport(
+    def _to_server_and_underlying_transport(
         self,
     ) -> tuple[FastMCP[Any], ClientTransport]:
-        """Get the server and transport for the server."""
+        """Turn the Transforming MCPServer into a FastMCP Server and also return the underlying transport."""
         from fastmcp import FastMCP
 
         transport: ClientTransport = super().to_transport()  # pyright: ignore[reportUnknownMemberType, reportAttributeAccessIssue, reportUnknownVariableType]
@@ -108,8 +108,10 @@ class _TransformingMCPServerMixin(FastMCPBaseModel):
         return wrapped_mcp_server, transport
 
     def to_transport(self) -> ClientTransport:
-        """Get the transport for the server."""
-        return self._to_server_and_transport()[1]
+        """Get the transport for the transforming MCP server."""
+        from fastmcp.client.transports import FastMCPTransport
+
+        return FastMCPTransport(mcp=self._to_server_and_underlying_transport()[0])
 
 
 class StdioMCPServer(BaseModel):

src/fastmcp/utilities/mcp_config.py

@@ -32,7 +32,7 @@ def mcp_server_type_to_servers_and_transports(
     transport: ClientTransport
 
     if isinstance(mcp_server, TransformingRemoteMCPServer | TransformingStdioMCPServer):
-        server, transport = mcp_server._to_server_and_transport()
+        server, transport = mcp_server._to_server_and_underlying_transport()
     else:
         transport = mcp_server.to_transport()
         server = FastMCP.as_proxy(backend=transport)