diff --git a/internal/cmd/command.harness.go b/internal/cmd/command.harness.go
index 61108d2..d9fb0c4 100644
--- a/internal/cmd/command.harness.go
+++ b/internal/cmd/command.harness.go
@@ -110,7 +110,7 @@ func selectHarnesses(ctx *CommandContext, flags cmd.HarnessFlags, setup bool) ([
 		Value(&names).
 		Validate(func(names []string) error {
 			if len(names) == 0 {
-				return errors.New("choose at least one harness")
+				return errors.New("choose at least one harness (space to select, enter to confirm)")
 			}
 			return nil
 		}).