The “description” field of a task doesn’t allow multiple persons to edit it at the same time. It’s not a collaborative-friendly tool. Therefore, what happens when multiple people work on the same task at the same time, they end up overwriting the description (last edit wins)
The “best” way to handle that, is to change the behaviour and make the description field “collaborative-friendly” by detecting conflicts and managing them (there are several ways to do that, but I won’t go into technicals atm)
Another (simpler) way, would be to show an indicator that makes it obvious that someone (and, ideally, whom) is currently editing the document. That would help people avoid overwriting someone else’s description.
Such indicator would be quite useful, and is a simple yet effective way of avoiding such conflicts.