lightly holding the charger in place well enough to maintain contact yet easily removed if the cable is pulled without damaging cable or device. anything after that is bonus and outside the scope of magsafe's use. the magnets on my desktop multi-device charger do not meet that requirement as they are significantly stronger than Magsafe connections.
It works great to support the entire weight of the phone on your desk or a dashboard, even when driving a fast car or riding a bike (unless you crash of course). But it's 1-2 orders of magnitude less force than required to resist pulling it out of your pocket.