Push notifications are an extremely powerful tool, but they are a sword that can from both sides. In fact, annoying or too many notifications are the primary reason why people uninstall mobile apps, or disable such notifications (and thus they lose all their effectiveness). Notifications are powerful because they help you communicate directly with users and deliver timely messages that can prompt actions or engagement. Your developer needs to understand the implications of using notifications, both their usefulness, when and how to often to send them and measuring their effectiveness or results so that you can adjust depending on how your audience reacts.