diff --git a/tests/plugins/test_a2a_schema_registration.py b/tests/plugins/test_a2a_schema_registration.py
index 6068b62fc7..76f9a3819d 100644
--- a/tests/plugins/test_a2a_schema_registration.py
+++ b/tests/plugins/test_a2a_schema_registration.py
@@ -35,7 +35,8 @@ def test_a2a_call_schema_round_trips_through_tool_describe(monkeypatch):
     monkeypatch.setattr(
         tool_search,
         "is_deferrable_tool_name",
-        lambda name: name == "a2a_call",
+        # #97979 added the defer_tools positional (curated-set override).
+        lambda name, defer_tools=None: name == "a2a_call",
     )
 
     described = json.loads(