McGee has not yet been given a specific job title.
"We feel that bringing the experience, past successes and baseball savvy that these three gentlemen possess to our Major League coaching staff will be a strong benefit to our ball club," president of baseball operations John Mozeliak said. "Whether it's coaching, teaching, game analysis, game planning, etc., these three men bring a wealth of knowledge and experience to our team."
Oquendo's return follows a two-year hiatus in which he recovered from multiple knee surgeries and served as a special assistant to the general manager. In that role, Oquendo, 54, worked primarily with Minor League players at the club's Florida complex. For health reasons, Oquendo declined previous overtures to return to the Major League staff, even when offered the chance to step in to a different role.
Before taking a leave of absence in March 2016, Oquendo spent 16 seasons as the Cardinals' third-base coach. His playing career spanned 12 seasons, the majority of which were with St. Louis.
McGee's 18-year career included 13 seasons with the Cardinals, who later hired him as a special assistant to the GM in 2013. He has become a regular guest instructor at Spring Training, and he made frequent visits to the organization's affiliates to assist with instruction.
McGee, named the National League's Most Valuable Player in 1985, has been a fan favorite in St. Louis for years. The 58-year-old former switch-hitter was voted into the Cardinals' Hall of Fame as part of the club's inaugural 2014 class.
Shildt, 48, joined Matheny's staff in 2017 as a quality-control coach and took over as third-base coach when the club shuffled staff assignments in June. Shildt, who will be Matheny's third bench coach, managed eight seasons in the Cardinals' farm system.
The club did not intend to name a new bench coach until Bell recently informed the organization that he would be accepting a job with the Giants. The Cardinals' search for a pitching coach and bullpen coach continues.
Additionally, the Cardinals announced that Ron "Pop" Warner will return to his role as assistant field coordinator. Warner joined the Major League coaching staff as part of that June shakeup.