diff --git a/src/fastmcp/server/server.py b/src/fastmcp/server/server.py
index d72c0351a..70b2079ff 100644
--- a/src/fastmcp/server/server.py
+++ b/src/fastmcp/server/server.py
@@ -41,6 +41,7 @@ from starlette.requests import Request
 from starlette.responses import Response
 from starlette.routing import BaseRoute, Route
 
+import fastmcp
 import fastmcp.server
 import fastmcp.settings
 from fastmcp.exceptions import NotFoundError
@@ -161,7 +162,9 @@ class FastMCP(Generic[LifespanResultT]):
 
         self.dependencies = dependencies
         self._cache = TimedCache(
-            expiration=datetime.timedelta(seconds=cache_expiration_seconds or 0)
+            expiration=datetime.timedelta(
+                seconds=self.settings.cache_expiration_seconds
+            )
         )
         self._mounted_servers: dict[str, MountedServer] = {}
         self._additional_http_routes: list[BaseRoute] = []
diff --git a/src/fastmcp/settings.py b/src/fastmcp/settings.py
index 04c830b27..1a3fc443a 100644
--- a/src/fastmcp/settings.py
+++ b/src/fastmcp/settings.py
@@ -170,7 +170,7 @@ class ServerSettings(BaseSettings):
         ),
     ] = []
 
-    # cache settings (for checking mounted servers)
+    # cache settings (for getting attributes from servers, used to avoid repeated calls)
     cache_expiration_seconds: float = 0
 
     # StreamableHTTP settings
diff --git a/tests/server/test_mount.py b/tests/server/test_mount.py
index 090666ccc..97c2efd3e 100644
--- a/tests/server/test_mount.py
+++ b/tests/server/test_mount.py
@@ -304,6 +304,19 @@ class TestDynamicChanges:
         tools = await main_app.get_tools()
         assert "sub_temp_tool" not in tools
 
+    async def test_cache_expiration(self):
+        main_app = FastMCP("MainApp", cache_expiration_seconds=2)
+        sub_app = FastMCP("SubApp")
+        tools = await main_app.get_tools()
+        assert len(tools) == 0
+
+        @sub_app.tool
+        def sub_tool():
+            return "sub_tool"
+
+        tools = await main_app.get_tools()
+        assert len(tools) == 0
+
 
 class TestResourcesAndTemplates:
     """Test mounting with resources and resource templates."""