diff --git a/pkg/keyspace/tso_keyspace_group.go b/pkg/keyspace/tso_keyspace_group.go
index 457c11edcfb..54887c762cb 100644
--- a/pkg/keyspace/tso_keyspace_group.go
+++ b/pkg/keyspace/tso_keyspace_group.go
@@ -1013,6 +1013,7 @@ func (m *GroupManager) FinishMergeKeyspaceByID(mergeTargetID uint32) error {
 	return nil
 }
 
+// GetKeyspaceGroupPrimaryByID returns the primary node of the keyspace group by ID.
 func (m *GroupManager) GetKeyspaceGroupPrimaryByID(id uint32) (string, error) {
 	// default keyspace group: "/ms/{cluster_id}/tso/00000/primary".
 	// non-default keyspace group: "/ms/{cluster_id}/tso/keyspace_groups/election/{group}/primary".
diff --git a/server/apiv2/handlers/tso_keyspace_group.go b/server/apiv2/handlers/tso_keyspace_group.go
index a5265ca7e02..23a5528d2ce 100644
--- a/server/apiv2/handlers/tso_keyspace_group.go
+++ b/server/apiv2/handlers/tso_keyspace_group.go
@@ -486,6 +486,7 @@ func SetPriorityForKeyspaceGroup(c *gin.Context) {
 	c.JSON(http.StatusOK, nil)
 }
 
+// GetKeyspaceGroupPrimaryByID gets primary of keyspace group by ID.
 func GetKeyspaceGroupPrimaryByID(c *gin.Context) {
 	id, err := validateKeyspaceGroupID(c)
 	if err != nil {