A bit more compact and nearly readable -

$schema->resultset("UserScenario")->update_or_create(
  {
      name        => $user_scenario->{name},
    ( description => $user_scenario->{description} ) x!! $user_scenari
+o->{description},
  },
  {   key         => "u_user_scenario_name" },
);
[download]

- if it wasn't for the "Highlander's List Asserter" (x!!) "secret operator", which Aristotle presented as the "boolean list squash operator" ;-)