Sealing a downhole tool

Techniques for sealing an annulus between a well tool and a tubular include moving the well tool through a wellbore in a run-in position, the well tool including a seal and a sleeve carried on the mandrel, and covering, in the run-in position, an exterior surface of the seal opposite an interior surface of the seal that faces the mandrel; landing the well tool in a tubular that includes a shoulder on an inner surface of the tubular and a seal bore on the inner surface of the tubular, the sleeve adjacent the shoulder upon landing the well tool; and receiving a force that moves a portion of the well tool further downhole to expose at least a part of the seal to the inner surface of the tubular to create a seal between an exterior surface of the well tool and the inner surface of the tubular.