fix: improve server name parsing in tool calls (#65)

Author: Henry-Jessie

src/mcp_agent/mcp/mcp_aggregator.py

@@ -267,7 +267,17 @@ async def call_tool(
         local_tool_name: str = None
 
         if SEP in name:  # Namespaced tool name
-            server_name, local_tool_name = name.split(SEP, 1)
+            parts = name.split(SEP)
+            
+            for i in range(len(parts) - 1, 0, -1):
+                potential_server_name = SEP.join(parts[:i])
+                if potential_server_name in self.server_names:
+                    server_name = potential_server_name
+                    local_tool_name = SEP.join(parts[i:])
+                    break
+                
+            if server_name is None:
+                server_name, local_tool_name = name.split(SEP, 1)
         else:
             # Assume un-namespaced, loop through all servers to find the tool. First match wins.
             for _, tools in self._server_to_tool_map.items():