diff --git a/config/testdata/config.yml b/config/testdata/config.yml
index 118278a..890a01b 100644
--- a/config/testdata/config.yml
+++ b/config/testdata/config.yml
@@ -6,7 +6,7 @@ core:
   worker_num: 0 # default worker number is runtime.NumCPU()
   queue_num: 0 # default queue number is 8192
   max_notification: 100
-  sync: false # set true if you need get error message from fail push notification in API response.
+  sync: false # set true if you need get error message from fail push notification in API response. It only works when the queue engine is local.
   feedback_hook_url: "" # set a hook url if you need get error message asynchronously from fail push notification in API response.
   feedback_timeout: 10 # default is 10 second
   mode: "release"