A lot of discussion happens around user stories during Sprint Planning sessions. Sometimes there is a discrepancy between what gets discussed and what gets implemented during the Sprint. This is because something was discussed but not captured somewhere. We need to close this loop and make sure that that capturing happens. I am not talking about recording some fancy audio-video tool. I am referring to capturing this discussion in the user stories themselves.
As you already know, user stories are only reminders for conversations and not be-all / end-all. There are details that are left out of user stories in the favour of discussion. When that discussion happens, we need to make sure that the conclusion is captured in the user stories. It could result in updating of the acceptance criteria. Or if the discussion was around technical aspects that need to be handled in a certain manner, the developer creates technical tasks for himself under the same story.
The key point is that whatever was discussed and agreed upon gets captured. During the sprint, when you get to that story, you should be able to look at it and know for sure what needs to be done in order to be done with the story. This helps in doing a good QA and UAT as there is a firm reference to verify against.