Burins, Scorpers and Gravers
It depends upon what kind of groove you want in the plate; there are tools with different points: square, lozenge, round and oval. Also there are "multiliners" and tint-tools. The shape of the point can be seen in the printed line. The boundary of the line will be sharper as the point is less round. Multi Liners are used for multiple lines perfect parallel to each other.