Voth (shoulder) was activated off the 10-day injured list Sunday.
Voth has been sidelined with shoulder tendinitis since July 21 but will join the Nationals after a three-game rehab stint. The 27-year-old had a 4.35 ERA, 1.21 WHIP and 20:6 K:BB in four starts for Washington, but he should slide into a bullpen role for the stretch run, per Mark Zuckerman of MASN Sports.