diff --git a/arkindex/dataimport/api.py b/arkindex/dataimport/api.py
index 5b536c049aed93bcbdd5533a1861f66582535f95..e25952b77f7de9530f2056e01e9e9ba7563f7855 100644
--- a/arkindex/dataimport/api.py
+++ b/arkindex/dataimport/api.py
@@ -1245,7 +1245,6 @@ class ListProcessElements(CustomPaginationViewMixin, CorpusACLMixin, ListAPIView
         )
 
 
-@extend_schema(tags=['ml'])
 class UpdateWorkerActivity(GenericAPIView):
     """
     Makes a worker (internal user) able to update its activity on an element
@@ -1270,10 +1269,16 @@ class UpdateWorkerActivity(GenericAPIView):
         }
 
     @extend_schema(
+        tags=['ml'],
+        responses={
+            200: DataImportSerializer,
+            409: None,
+        },
         operation_id='UpdateWorkerActivity',
         description=(
             'Updates the activity of a worker version on an element.\n\n'
-            'The user must be **internal** to perform this request.'
+            'The user must be **internal** to perform this request.\n\n'
+            'A **HTTP_409_CONFLICT** is returned in case the body is valid but the update failed.'
         ),
     )
     def put(self, request, *args, **kwarg):