The JR Pass can be convenient and cost-effective if you’re planning to travel on JR trains a lot throughout your trip in Japan - particularly if you want to experience a bullet train.
It is worth noting the JR Pass can only be purchased in 7, 14 or 21-day increments and must be purchased before you leave your home country (and don’t forget to factor in delivery time, too!).
However, if you only plan to stay within central Tokyo, the JR Pass is unlikely to offer any real savings. A prepaid SUICA card or the Tokyo Subway Pass may be better options.