  We address the characterization of molecular nanomagnets at the quantum level
and analyze the performance of local measurements in estimating the physical
parameters in their spin Hamiltonians. To this aim, we compute key quantities
in quantum estimation theory, such as the classical and the quantum Fisher
information, in the prototypical case of an heterometallic antiferromagnetic
ring. We show that local measurements, performed only on a portion of the
molecule, allow a precise estimate of the parameters related to both magnetic
defects and avoided level crossings.
