From c89384784607b8409799495f00ac6fa22e89142d Mon Sep 17 00:00:00 2001
From: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
Date: Sat, 7 Jun 2025 17:32:50 -0400
Subject: [PATCH 1/3] Respect cache setting, set default to 1

---
 src/fastmcp/server/server.py | 7 ++++++-
 src/fastmcp/settings.py      | 4 ++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/fastmcp/server/server.py b/src/fastmcp/server/server.py
index 9928ad152..4395a7aca 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
@@ -131,6 +132,8 @@ class FastMCP(Generic[LifespanResultT]):
         tools: list[Tool | Callable[..., Any]] | None = None,
         **settings: Any,
     ):
+        if cache_expiration_seconds is not None:
+            settings["cache_expiration_seconds"] = cache_expiration_seconds
         self.settings = fastmcp.settings.ServerSettings(**settings)
 
         # If mask_error_details is provided, override the settings value
@@ -148,7 +151,9 @@ class FastMCP(Generic[LifespanResultT]):
         self.tags: set[str] = tags or set()
         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 96939d11c..3c66ad3ae 100644
--- a/src/fastmcp/settings.py
+++ b/src/fastmcp/settings.py
@@ -170,8 +170,8 @@ class ServerSettings(BaseSettings):
         ),
     ] = []
 
-    # cache settings (for checking mounted servers)
-    cache_expiration_seconds: float = 0
+    # cache settings (for getting attributes from servers, used to avoid repeated calls)
+    cache_expiration_seconds: float = 1
 
     # StreamableHTTP settings
     json_response: bool = False

From 012fccb1ff073c25d15c02b32c65170795330b22 Mon Sep 17 00:00:00 2001
From: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
Date: Sat, 7 Jun 2025 17:36:13 -0400
Subject: [PATCH 2/3] Restore default to zero

---
 src/fastmcp/settings.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/fastmcp/settings.py b/src/fastmcp/settings.py
index 3c66ad3ae..f39c82ff1 100644
--- a/src/fastmcp/settings.py
+++ b/src/fastmcp/settings.py
@@ -171,7 +171,7 @@ class ServerSettings(BaseSettings):
     ] = []
 
     # cache settings (for getting attributes from servers, used to avoid repeated calls)
-    cache_expiration_seconds: float = 1
+    cache_expiration_seconds: float = 0
 
     # StreamableHTTP settings
     json_response: bool = False

From e7672bf0bc9f79f724ece9985a8f15502b15f3d0 Mon Sep 17 00:00:00 2001
From: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
Date: Sat, 7 Jun 2025 17:37:48 -0400
Subject: [PATCH 3/3] Update test_mount.py

---
 tests/server/test_mount.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

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."""