Ciriaco, 28, was on Kansas City's Opening Day roster primarily as a backup for second baseman Omar Infante, who's had a troublesome right elbow.
"We wanted to try to provide some insurance if Omar's elbow continued to flare up. It hasn't and he feels really good. We needed that 12th pitcher so we went ahead and made the move," manager Ned Yost said.
The Royals have 10 days in which to trade, release or put Ciriaco on waivers.
"But release isn't in the option," Yost said.
The Royals would like to keep Ciriaco in the organization, but they couldn't ship him to Triple-A Omaha because he's out of options. That puts him in limbo for 10 days, the same fate that befell outfielder Carlos Peguero recently. Peguero eventually got through the 10-day period and was assigned to Omaha.
With Ciriaco out, that means the Royals' only backup infielder is Danny Valencia, primarily a third baseman who also played first base in the Minors. Valencia, however, did spend time at second base in Spring Training and could fill in if necessary.
Also, if shortstop Alcides Escobar had to leave a game because of injury, Yost is prepared to move Infante to shortstop and use Valencia at second.
"That would get us through the day," Yost said.
There are other infielders available at Omaha as well.
"We've got Jason Donald, hopefully we'll have Ciriaco back down there, we've got Christian Colon and Johnny Giavotella if it's a second-base spot," Yost said. "We definitely have options."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.