"We're just looking for someone who can come off the bench with a little bang," manager Brian Snitker said.
d'Arnaud was hitting .375 (3-for-8) with two walks and five runs scored for Atlanta this year after batting .245 with one home run and 21 RBIs in 84 games with the Braves in 2016.
Adams was drafted by the Royals and made it to the Major Leagues with them as a September callup in 2014. He got three at-bats that month, but he hadn't been back in the big leagues since.
"I was excited, ecstatic, kind of at a loss for words," Adams said. "I got a call from an unknown number while I was in the shower. I thought it was a telemarketer at first, but luckily [Triple-A Gwinnett manager Damon Berryhill] left a voicemail."
Danny Knobler is a contributor to MLB.com based in New York.