If you rewrite the same agenda request every week, you are typing the template every time. The template is the part that never changes. The meeting is the part that does.
Save the structure, not the request
Put the format in custom instructions, or in a Project's instructions if you want it scoped to one team:
When I ask for a meeting agenda, always use: 1) Wins since last meeting 2) Blockers 3) Decisions needed today 4) Next steps with owners and dates. Under 200 words unless I say otherwise.Open the web version to copy this cleanly. Copying out of an inbox tends to drag stray line breaks with it, and this one goes into a settings field where that shows up.
Then the ask is four words
"Agenda for Thursday's sync."
That is the whole prompt. The structure is already loaded, so the only thing you supply is which meeting.
The word limit does more than it looks like it does. Without it you get an agenda nobody reads to the end. Under 200 words pushes the decisions to the front, which is the only part of an agenda that changes what happens in the room.
Why it compounds
Custom instructions carry into every new chat. Write the format once and every agenda from then on arrives in it, including the ones you ask for from your phone in the ten minutes before the meeting.
What to watch for
Instructions apply broadly. A meeting-agenda rule sitting in your global custom instructions will occasionally get reached for in unrelated chats. Scoping it to a Project avoids that and lets you run different formats for different teams.