Terms were not disclosed.
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"A very athletic safety," head coach Jason Garrett said of Pool, via the team's official website. "We have familiarity with him. He played in (defensive coordinator Rob Ryan's) system, he played for Jerome Henderson in Cleveland, so we know him. He's a guy we spoke to last year during that abbreviated free agency period."
Pool played the last two seasons for the New York Jets after five seasons with Cleveland, where he played for Ryan and Henderson.
Pool had 36 tackles and an interception last season. In 100 career games with Cleveland (2005-09) and the Jets (2010-11), he has 365 tackles with 13 interceptions.
Cleveland drafted Pool in the second round out of Oklahoma in 2005. Earlier this week, Dallas agreed to a five-year deal with cornerback Brandon Carr.
The Associated Press contributed to this report.