Triple-A Rochester reinstated Eder (undisclosed) from its 7-day injured list Wednesday and assigned him to Double-A Harrisburg.
Eder made his organizational debut later that day, striking out a batter and allowing one hit and no walks over two scoreless innings. The 26-year-old lefty occupies a spot on the Nationals' 40-man roster, but he may not get a look with the big club over the final two weeks of the season unless the Washington pitching staff is decimated by injuries.