Jones, 29, had been hitting .137 with a .219 on-base percentage and a .221 slugging percentage over 57 games as a reserve outfielder and designated hitter.
Jones has a career OPS of .742 against left-handed pitchers, suggesting he could serve as a late-game option against lefty relievers. The Red Sox, meanwhile, have outfielders with a .784 OPS against left-handed pitching but have utilized Jarren Duran sparingly in those matchups.
Boston added a 40-man roster item by designated left-handed reliever Danny Coulombe for assignment just before the All-Star break, a move that has not yet been officially documented in team transactions.
The trade deadline for major-league teams is August 3.
Further details on this development are forthcoming.