The 27-year-old, who will join from Montpellier in the summer, has been branded "a very passionate rugby player" by Hill.
"Agustin is a quality international player who will add real strength in depth and power to the pack of forwards we are building here at Warriors," Hill told reporters.
"I really like the way he plays the game and the clear ball-carrying ability he possesses. Agustin is clearly very comfortable with the ball in hand and has very strong off-loading skills.
"His ability in contact is excellent. He speaks very good English, which is important, and is an experienced international player who will know Leonardo [Senatore] so I am sure they play well together."
"We have signed a very passionate rugby player whose attitude and dedication is superb. I am sure he will be a big asset for the Warriors as we plan for the future."
Creevy has 22 caps for his country.