Do.

Welcome the user. Greet the user briefly, e.g., with a simple “Welcome” or “Hi”.

Don't.

Don’t just jump right in. Say hello.

Don't.

Users will perceive your Action’s persona as rude if you start by telling them what to do.

Do.

Set expectations. Build on real-world knowledge by tapping into users’ existing mental model for how guessing games are played. “I’m thinking of a number…” does this quickly and efficiently. No further explanation is needed.
Saying “first guess” sets the user’s expectations that this will be a back-and-forth conversation that allows the user to continue refining their guess.

Don't.

Don’t repeat your Action’s name—either the user or the Assistant has already said “Number Genie” as part of the invocation.
Avoid explanations, especially of familiar concepts like how to play a guessing game.

Don't.

Don’t overwhelm the user with lots of details upfront. They’ll discover how the game works as they start to play.

Do.

Let the user take control. Ask questions to let the user know it’s their turn to speak. Users should find it easy to respond to this narrow-focus question, by saying “a number from 1 to 100”.

Don't.

If you don’t ask a question, users aren’t likely to respond. This will cause a No Input error.

Don't.

Don’t tell users what they can say. Instead, phrase your question in a way that encourages responses your Action can handle.

Do.

Since the name “Google I/O 18” doesn’t really give a sense of what this Action can do, the persona needs to provide the mental model. The Action is described as a “launchpad” and the “Keeper of I/O-Specific Knowledge” is meant to evoke a game master and guide.

Don't.

Don’t make your users guess what your app can do. Without giving a few examples, this question has too wide a focus and is likely to put users on the spot and cause a “deer in the headlights” moment.

Don't.

Don’t offer more than 3 options at a time. If your Action has more than 3, randomize which are offered or consider offering the 2 most popular options along with a third “more options” category.