Barraclough was recalled from Double-A Harrisburg on Friday.
Barraclough was activated off the injured list and sent to Harrisburg during the All-Star break and returns to the Nationals after allowing two runs over 6.2 Eastern League frames. The 29-year-old was having the worst year of his major-league career with a 6.39 ERA and 1.74 WHIP in 32 outings prior to his demotion.