The College of Lore bard has the Cutting Words feature (PHB, p. 54-55):
Also at 3rd level, you learn how to use your wit to distract, confuse, and otherwise sap the confidence and competence of others. When a creature that you can see within 60 feet of you makes an attack roll, an ability check, or a damage roll, you can use your reaction to expend one of your uses of Bardic Inspiration, rolling a Bardic Inspiration die and subtracting the number rolled from the creature’s roll. You can choose to use this feature after the creature makes its roll, but before the DM determines whether the attack roll or ability check succeeds or fails, or before the creature deals its damage. The creature is immune if it can’t hear you or if it’s immune to being charmed.
I took this to mean that the bard would know what the final result of the roll was, my DM took it to mean I don't have any information of the roll, and for the night we met in the middle and I was allowed to know the roll but not any modifiers applied to it.
How much information on the attack roll is the bard privy to when deciding to use Cutting Words?
Best Answer
According to Jeremy Crawford in this conversation...
When asked to confirm that "[the] DM must communicate only the number on the dice (without [any added] modifiers)," Crawford responded...
So the bard (or any creature using a similar feature) is told or shown the number rolled on the die, not any modifiers which would apply to the roll. To be clear, then, they are not told the total.