diff --git a/litellm/proxy/_experimental/mcp_server/mcp_server_manager.py b/litellm/proxy/_experimental/mcp_server/mcp_server_manager.py
index 793419e2270..872b1fb5262 100644
--- a/litellm/proxy/_experimental/mcp_server/mcp_server_manager.py
+++ b/litellm/proxy/_experimental/mcp_server/mcp_server_manager.py
@@ -5139,7 +5139,9 @@ class MCPServerManager:
         return prefixed_tools
 
     def get_listed_tool(self, server: MCPServer, name: str) -> MCPTool | None:
-        listed: Final = self._listed_tools_by_server_id.get(server.server_id, {})
+        listed: Final = self._listed_tools_by_server_id.get(server.server_id)
+        if not listed:
+            return None
         return listed.get(name) or listed.get(strip_known_server_prefix(name, server))
 
     def _create_prefixed_prompts(
diff --git a/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_guardrail_usage_monitor.py b/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_guardrail_usage_monitor.py
index 24e6d2de10d..956f87f0da1 100644
--- a/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_guardrail_usage_monitor.py
+++ b/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_guardrail_usage_monitor.py
@@ -48,6 +48,7 @@ def _bare_manager() -> MOD.MCPServerManager:
     reaches the guardrail hooks; they have their own coverage elsewhere.
     """
     mgr = MOD.MCPServerManager.__new__(MOD.MCPServerManager)
+    mgr._listed_tools_by_server_id = {}
     mgr.check_allowed_or_banned_tools = lambda name, server: True
     mgr.validate_allowed_params = lambda tool_name, arguments, server: None