  As demonstrated by Planck, SPT, and ACT, the abundance of
Sunyaev-Zeldovich-detected galaxy clusters across mass and redshift is a
powerful cosmological probe. Upcoming experiments such as the Simons
Observatory (SO) will detect over an order of magnitude more objects than what
previous experiments have found, thereby providing an unprecedented
constraining potential. However, in order for this potential to be realised,
the cluster detection and analysis pipelines will have to be built and
understood to a much higher level of accuracy than has been demonstrated to
date. Here we discuss ongoing efforts towards the accurate modelling of tSZ
cluster counts, focusing on several improvements regarding optimisation bias,
covariance estimation, and foreground deprojection, which are implemented in
the publicly-available SZiFi package. Next, we briefly discuss the application
of these improved cluster detection methods to Planck data. Finally, we
introduce cosmocnc, a new cluster number count likelihood code that will be
publicly available soon.
