diff --git a/docs/developer_guides/chap07_query_coordinator.md b/docs/developer_guides/chap07_query_coordinator.md
index 592b21435c..73a208f98d 100644
--- a/docs/developer_guides/chap07_query_coordinator.md
+++ b/docs/developer_guides/chap07_query_coordinator.md
@@ -257,6 +257,7 @@ type QueryNode interface {
 	ReleaseSegments(ctx context.Context, req *querypb.ReleaseSegmentsRequest) (*commonpb.Status, error)
   // GetSegmentInfo requests segment info
 	GetSegmentInfo(ctx context.Context, req *querypb.GetSegmentInfoRequest) (*querypb.GetSegmentInfoResponse, error)
+  // GetMetrics gets the metrics about QueryNode.
 	GetMetrics(ctx context.Context, in *milvuspb.GetMetricsRequest, opts ...grpc.CallOption) (*milvuspb.GetMetricsResponse, error)
 }
 ```