The changes will start reaching new users in October, and should extend to existing users in early 2019.

While Google didn't say as much, the clampdown appears to be a reaction to word that its previous policies let third-party apps scan Gmail inboxes without much clarity for users. This change should make it clear what apps really want. Google is also using the fine-grained control as a way to promote better explanations to users. While it's not mandating elaborate descriptions, it's hoping the item-by-item permissions will encourage clearer dialog and prevent any rude surprises.