Add the context.
The agent does not know your reader, your deadline, or the last thing that happened. It will fill the gaps with something typical. Typical is rarely your case.
Add only the facts that change the answer. Audience, prior message, hard dates, words you must not use. Leave out your life story.
Facts that move the draft
You are a calm colleague. Write a four-sentence email to a supplier who missed a delivery. Context: the supplier is Mara at Northline; the pallet was due Tuesday; we still need it by Friday morning for a class of 18; we have used them for a year without trouble. Goal: a new date we can both see, no blame.
Notice what the extra lines change: the name, the Friday, the history.
Hi Mara — Tuesday’s pallet from Northline did not arrive, and we still need it by Friday morning for a class of 18. You have been steady with us for a year, so I am assuming this is a slip, not a pattern. What date can you confirm? Friday still works if you can lock it.
A habit of listing the facts the agent cannot see. If a fact would change the answer, it belongs in the brief.