  Planets can affect debris disk structure by creating gaps, sharp edges,
warps, and other potentially observable signatures. However, there is currently
no simple way for observers to deduce a disk-shepherding planet's properties
from the observed features of the disk. Here we present a single equation that
relates a shepherding planet's maximum mass to the debris ring's observed width
in scattered light, along with a procedure to estimate the planet's
eccentricity and minimum semimajor axis. We accomplish this by performing
dynamical N-body simulations of model systems containing a star, a single
planet, and a disk of parent bodies and dust grains to determine the resulting
debris disk properties over a wide range of input parameters. We find that the
relationship between planet mass and debris disk width is linear, with
increasing planet mass producing broader debris rings. We apply our methods to
five imaged debris rings to constrain the putative planet masses and orbits in
each system. Observers can use our empirically-derived equation as a guide for
future direct imaging searches for planets in debris disk systems. In the
fortuitous case of an imaged planet orbiting interior to an imaged disk, the
planet's maximum mass can be estimated independent of atmospheric models.
