Assistant coaches decide things in parking lots and then forget who agreed. Write it down as a question.
Facts you both can check
Minutes in the last three games. The position you want to try. The date of the tournament. What you already told the player, if anything.
Then: start them, or keep the rotation, by Wednesday so we say one thing at practice.
Not a speech
Your assistant will draft something about development and culture. The other coach knows the speech. They need the call.
If the answer is no, say no in writing when you tell the parent — later, as a separate letter, with the decision you actually made.
Keep nicknames and vents off it
Whatever you call a parent in your own list is not a name that goes in a package. The player has a name on the roster. Use that.
If the other coach has no assistant, email is enough. You still have a thread when the season gets loud.