The Google assistant makes for a pretty awesome companion on the Pixel phones and Google Home, but it's still young and feels constrained by the very limited number of things it can do outside of Google's sandbox of supported services. During the October 4th announcement, Google declared plans to open up the platform in early December for developers to build their own services. Staying true to that schedule, the Actions on Google platform opened the door today, allowing developers to integrate their services. Google is also launching an early access program to begin testing new features and upcoming expansions.
Google is already working with an assortment of partners to bring new Conversation Actions, including news organizations like The Wall Street Journal and CNN, utility services like Todoist and WebMD, and even food service companies like Domino's Pizza. This list is still pretty short, but as more developers gain access, we should see some pretty rapid growth.
Two samples are already available: Number Genie and Eliza, but there are surely going to be hundreds or thousands of new actions fairly soon. There's no need to install Skills like you would with Alexa, the actions are simply available by name. Users can access custom actions by saying something like "Ok Google, talk to Number Genie." Strangely, the voice changes when you're interacting with custom actions.
Developers can create these interactive voice services using API.AI or Gupshup, or perform their own language processing with the transcribed commands from users. A YouTube playlist (embeded above) introduces the design and development of voice interfaces, and Google has posted sample code, best practices, and other documentation to get started. There's also a newsletter, Google+ community, and an actions-on-google tag on StackOverflow for developers looking to get even more information and advice.
Custom actions are only available on Google Home's version of the assistant for now, but they will expand to Pixel phones, Allo, and other implementations in the future. Google also announced plans to add support for making purchases, bookings, and other payment-related activities in the future. Developers interested in getting first crack at these features can apply to join the Actions on Google early access program.
Now we just have to wait and see what cool ideas turn up from developers – you know, once we're through the first couple-thousand actions that don't do anything, play pranks, or produce fart noises.
- Google Developers Blog