T cells are an essential cell type of our adaptive immune system, helping to both detect and eliminate pathogens that may have infected our bodies. This essential function is mediated by the T cell antigen receptor complex (TCR) expressed at the plasma membrane, which can interrogate the intracellular state of host cells by scanning for pathogen-derived peptides presented on the surface of host cells. For us to remain healthy, T cells must be able to respond extremely robustly to ensure a resolution of the diseased state, even when there are only a few TCR ligands expressed on the infected cells. In PNAS, Feng et al. show that exertion of force on the TCR during ligand binding is required for the extraordinary potency toward ligand binding observed in vivo.