diff --git a/bdledger/api/query.proto b/bdledger/api/query.proto
index da78a91..286fe9a 100644
--- a/bdledger/api/query.proto
+++ b/bdledger/api/query.proto
@@ -11,7 +11,7 @@ option java_multiple_files = true;
 
 service Query {
   rpc GetBlockByHash (GetBlockByHashRequest) returns (GetBlockByHashResponse);
-  rpc GetBlocks (BlocksRequest) returns (GetBlocksResponse);
+  rpc GetBlocks (BlocksRequest) returns (GetBlocksResponse); // start_timestamp is required
   rpc CountBlocks (BlocksRequest) returns (CountBlocksResponse);
   rpc GetTransactionByHash (GetTransactionByHashRequest) returns (GetTransactionByHashResponse);
   rpc GetTransactionByBlockHashAndIndex (GetTransactionByBlockHashAndIndexRequest) returns (GetTransactionByBlockHashAndIndexResponse);
@@ -43,7 +43,7 @@ message GetBlockByHashResponse {
 
 message BlocksRequest {
   string ledger = 1;
-  int64 start_timestamp = 2; // required
+  int64 start_timestamp = 2;
   int64 end_timestamp = 3;
   repeated BlockFilter filters = 4;
 }