"Doth the trick" is a phrase often used to describe something that works effectively or accomplishes its intended purpose. While there are several synonyms to express the same meaning, it is also important to understand the antonyms for this phrase to convey the opposite sense. Some of the antonyms for "doth the trick" include "ineffective," "inefficient," "inept," "useless," "inadequate," "insufficient," "unsatisfactory," "ineffectual," and "inoperable." These words distinctly suggest the inability of an action or entity to deliver the desired result. Therefore, choosing the right antonym can help to clearly communicate the exact opposite of "doth the trick" in a given scenario.