I think it's also okay to retcon a description. For example, a player might say:
Player: I try to convince the guard to let us through. I say, "Don't you know who we are? We're the Knights of the Golden Hart!"
DM: Make a Charisma check.
Player: Hm... Could I use Performance?
DM: Tell me how.
Player: I start telling him the story of our most famous exploit, when we slew the Wyvern of the Spire…
In this (made up) case, allowing the player to choose a skill, even when it didn't match their original narration, adds to the scene and could make for a memorable social encounter.