It isn't classic tolerance, and you won't typically see someone needing huge doses to get the same old effect. Antidepressants which raise serotonin can be associated with a withdrawal syndrome. This is not consistent, and people vary hugely in their sensitivity to this. Many people have some degree of withdrawal symptoms, and a small handful of people are exquisitely sensitive to antidepressant withdrawal, and literally need months to taper with even moderate discomfort. This is the exception, not the norm, but you should be aware of this.
Antidepressants have virtually no abuse potential.
Benzodiazepines are a class of medications which decrease anxiety. They are quite effective in this regard. They can also cause sedation and cause subtle cognitive or motor impairment. This is actually a very broad family of medications, with some taking effect rapidly and other not, and some staying in the body for a long time and others not. Benzodiazepines will reliably cause physiological dependence if blood levels are maintained beyond 7-30 days.