overconscientious

adjective

over·​con·​sci·​en·​tious ˌō-vər-ˌkän(t)-shē-ˈen(t)-shəs 

: unduly or excessively conscientious : giving more thoughtful attention to something than is necessary or appropriate

He can be overconscientious about following the rules.

To her overworked and exasperated teachers she was an overconscientious "slow learner" who kept trying to catch up …

—Tillie Olsen

Word History

First Known Use

1835, in the meaning defined above