diff --git a/force_bdss/core_driver_events.py b/force_bdss/core_driver_events.py
index d7b10c0026abc89c296769d93219923e40a140c8..6afa98f336c02c07307e6e6d519339d657a3234f 100644
--- a/force_bdss/core_driver_events.py
+++ b/force_bdss/core_driver_events.py
@@ -1,4 +1,6 @@
-from traits.api import HasStrictTraits, Tuple
+from traits.api import HasStrictTraits, Tuple, List, Instance, Float
+
+from force_bdss.core.data_value import DataValue
 
 
 class BaseDriverEvent(HasStrictTraits):
@@ -19,5 +21,6 @@ class MCOProgressEvent(BaseDriverEvent):
     """ The MCO driver should emit this event for every new evaluation that has
     been completed. It carries data about the evaluation, specifically the
     input data (MCO parameter values) and the resulting output (KPIs)."""
-    input = Tuple()
-    output = Tuple()
+    optimal_point = List(Instance(DataValue))
+    optimal_kpis = List(Instance(DataValue))
+    weights = List(Float())