Bolton went 0-1 with a 6.33 ERA in 16 appearances for the Pirates during his rookie season in 2023, striking out 22 batters in 21 1/3 innings.
Rivas, acquired in a trade with the San Diego Padres on Aug. 1, hit .229 with three home runs and 15 RBIs in 40 games with Pittsburgh.
Marcano, who can play shortstop, second base and in the corner outfield, was claimed by the Cleveland Guardians. Marcano appeared in 75 games for the Pirates in 2023 before tearing the ACL in his right knee in July. The 24-year-old hit .233 with three home runs and 16 RBIs last season.
Capra played in nine games for Pittsburgh after being acquired in a trade with the Toronto Blue Jays in April.