diff --git a/apps/emqx_ds_shared_sub/src/emqx_ds_shared_sub_proto.hrl b/apps/emqx_ds_shared_sub/src/emqx_ds_shared_sub_proto.hrl
index 2bb978c8b..c780ab193 100644
--- a/apps/emqx_ds_shared_sub/src/emqx_ds_shared_sub_proto.hrl
+++ b/apps/emqx_ds_shared_sub/src/emqx_ds_shared_sub_proto.hrl
@@ -3,13 +3,12 @@
 %%--------------------------------------------------------------------
 
 %% @doc Asynchronous messages between shared sub agent and shared sub leader
+%% These messages are instantiated on the receiver's side, so they do not
+%% travel over the network.
 
 -ifndef(EMQX_DS_SHARED_SUB_PROTO_HRL).
 -define(EMQX_DS_SHARED_SUB_PROTO_HRL, true).
 
-%% TODO
-%% Make integer keys on GA
-
 %% NOTE
 %% We do not need any kind of request/response identification,
 %% because the protocol is fully event-based.