I gave an enemy three beads of force, one of which was used against the PCs, two of which they now have.
The item says:
You can use an action to throw the bead up to 60 feet.
Is an attack roll necessary to accurately throw the bead where the thrower desires?
Generally we play on a grid, although not always, if that makes any difference.
I mention that the object being thrown is a bead of force, although I assume the same rules would apply to throwing a bead or anything else.
If an attack roll was required, the object's description would say so. There are no secret rules in DnD 5e.
Attack rolls are generally intended to check whether you hit a target that's either a creature or, much more rarely, an object. The targets are usually protected in some manner: a creature can be wearing armor of have a natural shell that's difficult to pierce, and most beings are interested in their survival enough to attempt to parry or dodge incoming blows and thrown weapons. Objects don't, but they typically lack critical weaknesses like organs that cause the whole thing to fail when damaged. Missed attacks also include glancing blows that technically touch the target but don't do any real damage.
Here, you're essentially trying to throw a bead into a particular 5×5 square - a much easier feat than hitting a creature, since the square can't parry or dodge the bead. As a GM, even if I wanted to houserule it, I wouldn't consider making it an attack roll because it defies the usual conventions of attacks --- there's no AC to hit, no damage roll to make --- but if the circumstances were particularly tricky (eg. an enemy is chewing on the throwing character's face at the time) I would instead make it a Dexterity check.
