To make room on their roster for Kottaras, the Royals designated infielder Tony Abreu for assignment.
Kottaras was designated for assignment last week by the A's in order to create a roster spot for John Jaso. The 29-year-old split last season between the Milwaukee Brewers and A's, hitting .211/.351/.415 with six doubles and nine home runs over 171 at-bats. Over parts of five seasons at the major league level he's hit .220/.320/.412.
Abreu spent the 2012 season with the Royals after signing as a free agent last winter. He hit .257/.284/.357 with four extra-base hits over 70 at-bats for Kansas City, but he spent a majority of his season with the team's Triple-A affiliate. In the minors he hit .322/.347/.492 with 36 doubles, five triples and nine home runs over 429 at-bats.