diff --git a/src/mcp/server/mcpserver/utilities/func_metadata.py b/src/mcp/server/mcpserver/utilities/func_metadata.py
index 96d25ec5ab..f8dcd70412 100644
--- a/src/mcp/server/mcpserver/utilities/func_metadata.py
+++ b/src/mcp/server/mcpserver/utilities/func_metadata.py
@@ -500,7 +500,7 @@ def _create_output_model(original_annotation: Any, type_expr: Any, func_name: st
         wrap_output = True
 
     # Handle GenericAlias types (list[str], dict[str, int], Union[str, int], etc.)
-    elif isinstance(type_expr, GenericAlias):
+    elif get_origin(type_expr) is not None:
         origin = get_origin(type_expr)
 
         if origin is dict:
diff --git a/src/mcp/server/sse.py b/src/mcp/server/sse.py
index d71ef25004..ca65e93254 100644
--- a/src/mcp/server/sse.py
+++ b/src/mcp/server/sse.py
@@ -15,6 +15,8 @@
 
     # Define handler functions
     async def handle_sse(request):
+    if scope["method"] == "HEAD":
+        return Response(media_type="text/event-stream", headers={"Cache-Control": "no-store"})
         async with sse.connect_sse(
             request.scope, request.receive, request._send
         ) as streams: