diff --git a/command/service/opts.go b/command/service/opts.go
index 7a5db67b79..8de8b173ef 100644
--- a/command/service/opts.go
+++ b/command/service/opts.go
@@ -446,8 +446,8 @@ func addServiceFlags(cmd *cobra.Command, opts *serviceOptions) {
 	flags.Var(&opts.restartPolicy.window, flagRestartWindow, "Window used to evaluate the restart policy")
 
 	flags.Uint64Var(&opts.update.parallelism, flagUpdateParallelism, 1, "Maximum number of tasks updated simultaneously (0 to update all at once)")
-	flags.DurationVar(&opts.update.delay, flagUpdateDelay, time.Duration(0), "Delay between updates")
-	flags.DurationVar(&opts.update.monitor, flagUpdateMonitor, time.Duration(0), "Duration after each task update to monitor for failure")
+	flags.DurationVar(&opts.update.delay, flagUpdateDelay, time.Duration(0), "Delay between updates (ns|us|ms|s|m|h) (default 0s)")
+	flags.DurationVar(&opts.update.monitor, flagUpdateMonitor, time.Duration(0), "Duration after each task update to monitor for failure (ns|us|ms|s|m|h) (default 0s)")
 	flags.StringVar(&opts.update.onFailure, flagUpdateFailureAction, "pause", "Action on update failure (pause|continue)")
 	flags.Float32Var(&opts.update.maxFailureRatio, flagUpdateMaxFailureRatio, 0, "Failure rate to tolerate during an update")
 
diff --git a/command/swarm/opts.go b/command/swarm/opts.go
index af36a71673..ce5a9b1de0 100644
--- a/command/swarm/opts.go
+++ b/command/swarm/opts.go
@@ -168,8 +168,8 @@ func parseExternalCA(caSpec string) (*swarm.ExternalCA, error) {
 
 func addSwarmFlags(flags *pflag.FlagSet, opts *swarmOptions) {
 	flags.Int64Var(&opts.taskHistoryLimit, flagTaskHistoryLimit, 5, "Task history retention limit")
-	flags.DurationVar(&opts.dispatcherHeartbeat, flagDispatcherHeartbeat, time.Duration(5*time.Second), "Dispatcher heartbeat period")
-	flags.DurationVar(&opts.nodeCertExpiry, flagCertExpiry, time.Duration(90*24*time.Hour), "Validity period for node certificates")
+	flags.DurationVar(&opts.dispatcherHeartbeat, flagDispatcherHeartbeat, time.Duration(5*time.Second), "Dispatcher heartbeat period (ns|us|ms|s|m|h) (default 5s)")
+	flags.DurationVar(&opts.nodeCertExpiry, flagCertExpiry, time.Duration(90*24*time.Hour), "Validity period for node certificates (ns|us|ms|s|m|h) (default 2160h0m0s)")
 	flags.Var(&opts.externalCA, flagExternalCA, "Specifications of one or more certificate signing endpoints")
 	flags.Uint64Var(&opts.maxSnapshots, flagMaxSnapshots, 0, "Number of additional Raft snapshots to retain")
 	flags.Uint64Var(&opts.snapshotInterval, flagSnapshotInterval, 10000, "Number of log entries between Raft snapshots")