MOUNTAIN VIEW, CALIF.: When Google first introduced its phone-calling digital concierge Duplex in May, some thought it sounded too human. Others worried that it would secretly record calls with people.

The search giant says it has been working to address these concerns.

For starters, Google says that the bot will identify itself as an automated assistant upfront and will disclose that it’s recording calls. Human operators will be standing by should a call go off the rails.

As for Duplex’s tendency to use speech fillers like “ums” and “ahs,” Google notes that this technique improved the assistant’s ability to book appointments by interacting more naturally with humans on the other end of the line.

The search giant provided these and other details in a demonstration for reporters Tuesday ahead of the system’s gradual rollout this summer.

The company is taking great pains to assure that Duplex conforms to a set of principles around artificial intelligence it released earlier this month. Among them: only develop tools that are socially beneficial and that incorporate privacy by design.

“We’re not trying to trick people,” Scott Huffman, Google’s vice president of engineering for the Google Assistant, told reporters. He played a recording of an early Duplex prototype in which a computerized male voice tried to book a restaurant reservation for four, and filled an awkward silence with an off-kilter “Hello.”

“The system didn’t sound very good,” Huffman said. “People would hang up on it. They got uncomfortable with the conversation. The team began to iterate on, ‘How do we make it sound more natural?’ As they did that, with every step, we found that our success rate went up.”

Now, Duplex can book hair appointments, make restaurant reservations or check holiday business hours — the only tasks it is programmed to complete — four out of five times without intervention.

It identifies itself in a few different ways. In one sample call, Duplex began, “Hi, I’m calling to make a reservation. I’m Google’s automated booking service, so I’ll record the call.” In another, it starts, “Hi I’m the Google Assistant, calling to make a reservation for a client. This automated call will be recorded.”

In a test, an Associated Press reporter acted as a restaurant employee and objected to the call being recorded. The transcript went like this:

Duplex: “Hi, I’d like to make a reservation. I’m Google’s automated booking service, so I’ll record the call. Um, can I book a table for Saturday, the 30th?”

AP: “Uh, OK, but what if I don’t want the call to be recorded?”

Duplex: “OK, uh we’ll call you back on an unrecorded line.”

A human operator called back within minutes, completed the booking and said the restaurant would be opted out of receiving Duplex calls in the future.

Duplex’s initial rollout will only cover questions about holiday and weekend hours, limited to a select group of testers and businesses. The ability to book restaurants or hair appointments will follow later this summer.