  Hadronic $\tau$ decays are studied as probe of new physics. We determine the
dependence of several inclusive and exclusive $\tau$ observables on the Wilson
coefficients of the low-energy effective theory describing charged-current
interactions between light quarks and leptons. The analysis includes both
strange and non-strange decay channels. The main result is the likelihood
function for the Wilson coefficients in the tau sector, based on the up-to-date
experimental measurements and state-of-the-art theoretical techniques. The
likelihood can be readily combined with inputs from other low-energy precision
observables. We discuss a combination with nuclear beta, baryon, pion, and kaon
decay data. In particular, we provide a comprehensive and model-independent
description of the new physics hints in the combined dataset, which are known
under the name of the Cabibbo anomaly.
