“How’s your story on Smart Reply coming?” asked my editor, via email. After opening the Google Inbox app, which has replaced the Gmail app on my phone for over a week, I was given three options for a quick response: “It’s going good!” “Still working on it.” and “I haven’t heard anything yet.” With two taps of the screen I was able to let her know that I was “still working on it”

Smart Reply, Google’s latest addition to the Inbox app, was rolled out in early November. It provides users with three options for simple email replies based on the content of the received email. Once an option is selected, those preloaded responses can be edited before tapping “send.”

That two-tap email reply to my editor is exactly what the Google team was striving for when designing Google Inbox’s latest smartphone feature. Responding to emails on mobile devices can be laborious, but having a quick option–or even just the first sentence of a reply already written–shaves precious seconds off the mobile emailing experience.

During my weeklong experiment with Smart Reply it was rare to receive three options that all failed to communicate what I wanted to write. I realized that most of my email replies could be summed up in the 2-5 words suggested by the application, and those that required more attention often started with one of those three suggestions. For example, if I needed to tell my editor that there was a problem with this story, the “still working on it,” option could be easily followed by further explanation.

According to Google, Smart Reply’s development was the result of a collaborative experiment between the company’s research and product development teams.

“When we started we really didn’t know whether this was even possible with today’s technologies, and I’m really excited that we were able to get something out there,” said Greg Corrado, a senior research scientist on the Google Brain Team.

Corrado explains that Smart Reply was built atop layers of machine-learning technologies. The first layer identifies whether an email is fit for a quick response, weeding out mailing list items or lengthy emails that are unlikely to have a brief reply. The second layer scans the email and predicts the most likely responses, and the third ensures that the three suggestions are distinct.