  We generalize in several directions our recent analysis of the limitations to
the use of the effective field theory approach to study dark matter at the LHC.
Firstly, we study the full list of operators connecting fermion DM to quarks
and gluons, corresponding to integrating out a heavy mediator in the
$s$-channel; secondly, we provide analytical results for the validity of the
EFT description for both $\sqrt{s}=8$ {\rm TeV} and $14$ {\rm TeV}; thirdly, we
make use of a MonteCarlo event generator approach to assess the validity of our
analytical conclusions. We apply our results to revisit the current collider
bounds on the ultraviolet cut-off scale of the effective field theory and show
that these bounds are weakened once the validity conditions of the effective
field theory are imposed.
