Supersymmetric localization provides a powerful mechanism in gauge theories on curved backgrounds that allows for the exact, non-perturbative calculation of BPS observables. Kappa symmetry can be used in the D3/D5 and D3/D7 probe brane systems to holographically calculate similar BPS quantities. Confronting these two computations yields a novel precision test of the probe brane paradigm in the AdS/CFT correspondence.