A watchOS app gives users more detailed information or functionality than they can find in notification interfaces. Your watchOS app complements your iPhone app and is meant for quick interactions with your content. Use your watchOS app to display important information and to facilitate interactions with that information. Take advantage of Handoff to forward tasks back to iOS and macOS devices as needed.
Make your app’s interface highly glanceable. Organize text and images so that users can find the information they need quickly and easily.
Keep your app’s snapshot up to date. Your app’s snapshot is displayed in the Dock and when your app launches, so make sure it contains the most recent, relevant, and actionable information. A snapshot doesn't have to be the same view the user last saw, but it should always be instantly recognizable as your app. Don't show alerts or error states in snapshots.
Design your interface with snapshots in mind. Snapshot images in the Dock are displayed at roughly two-thirds of their normal size. Consider presenting your content differently if doing makes that content easier to read. Make sure that the font sizes you choose are legible at that reduced size.