While validating information, if something is missing or unclear, your app can instruct Siri to present choices, ask for confirmation, or request more information. At Siri’s discretion, certain tasks such as sending messages and making payments always require confirmation before the app can perform the task.

Information from your app’s response is spoken by Siri and appears in the Siri interface. If appropriate, your app can provide custom content for Siri to display. A fitness app, for example, might provide custom workout information.

Strive for a voice-driven experience that doesn’t require touching or looking at the screen. People don’t always look at the screen when using Siri. They may interact with Siri through a headset, through their car, or from across the room. To the extent possible, let users complete tasks without unlocking their phone.

Respond quickly and minimize interaction. People use Siri for convenience, so don't make them wait for a response. Your app should validate information and take action as quickly as possible after receiving a request. When clarification or additional information is needed, present efficient, focused choices that reduce the possibility of additional prompting.

Take people directly to content. Transitions from Siri to your app should go directly to the expected destination. Don’t show intermediary screens or messages that get in the way or slow people down.

Be relevant, accurate, and appropriate. Your app’s response should always be relevant to the current request and should accurately reflect people’s expectations. Never include content that might be considered offensive or demeaning.

Default to the safest and least expensive option. A response should never be deceiving or misrepresent information, especially when it has financial impact. For a purchase with multiple pricing levels, don’t default to the most expensive. At the point where a user is making a payment, don’t charge extra fees without informing them.

Increase accuracy with custom vocabulary. Your app can help Siri learn more about the actions your app performs by defining specific terms people might use in requests, such as contact names, photo tags, photo album names, ride options, and workout names. These terms should be nongeneric, unique to your app, and terms people might actually use when making a request. The vocabulary you provide should never include other app names, terms that are obviously connected with other apps, inappropriate language, or reserved phrases, such as “Hey Siri.” Note that any terms you define are used by Siri to help resolve requests, but aren’t guaranteed to be recognized.

Provide example requests. Provide Siri with example phrases to show in the guide that appears when you tap the Help button in the Siri interface. Use these phrases to teach people the easiest and most efficient way to use Siri with your app.

Make sure your custom interface integrates well with Siri. It’s fine to use your app’s colors, imagery, and other design elements to communicate your brand, but any custom interface elements should still feel like they belongs in Siri.

Don’t include your app name or icon in your custom interface. The system automatically shows this information.

Don’t advertise. Your app’s Siri experience should never include advertisements, marketing, or in-app purchase sales pitches.

Don’t attempt to mimic or manipulate Siri. Your app should never impersonate Siri, attempt to reproduce the functionality Siri provides, or provide a response that appears to come from Apple.

For implementation details, see SiriKit Programming Guide.