diff --git a/ui/metrics/metrics_proto/metrics.pb.go b/ui/metrics/metrics_proto/metrics.pb.go
index 5e144f4..6a664dc 100644
--- a/ui/metrics/metrics_proto/metrics.pb.go
+++ b/ui/metrics/metrics_proto/metrics.pb.go
@@ -1437,6 +1437,8 @@
 	return nil
 }
 
+// CriticalPathInfo contains critical path nodes's information.
+// A critical path is a path determining the minimum time needed for the whole build given perfect parallelism.
 type CriticalPathInfo struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
diff --git a/ui/metrics/metrics_proto/metrics.proto b/ui/metrics/metrics_proto/metrics.proto
index f7a836e..d95efa6 100644
--- a/ui/metrics/metrics_proto/metrics.proto
+++ b/ui/metrics/metrics_proto/metrics.proto
@@ -318,6 +318,8 @@
   repeated string mixed_build_disabled_modules = 2;
 }
 
+// CriticalPathInfo contains critical path nodes's information.
+// A critical path is a path determining the minimum time needed for the whole build given perfect parallelism.
 message CriticalPathInfo {
   // Real time which the build system spent
   optional uint64 elapsed_time = 1;