Methods are provided for modulating MRGPRX2 generally, or for treating a MRGPRX2 dependent condition more specifically, by contacting the MRGPRX2 or administering to a subject in need thereof, respectively, an effective amount of a compound having structure (I): or a pharmaceutically acceptable salt, isomer, hydrate, solvate or isotope thereof, wherein D, W, Z, R1, R2 and R3 are as defined herein. Pharmaceutical compositions containing such compounds, as well as the compounds themselves, are also provided.