Rebuild the missing context
Assume the recipient will not remember every date, promise, or earlier conversation. For a message about how to ask a coworker to cover your shift, use this factual base: state the item, task, route, date, duration, responsibility, and any expense or risk involved.
Say what needs to happen next
State the decision, information, or practical action you need and include a real deadline only when one exists. Make a direct request, offer the information needed to decide, and confirm the return or completion plan. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Avoid making urgency into pressure
Do not call the favor small when it costs time, money, access, or professional reputation. Do not ask someone to break a rule, share credentials, sign falsely, transport unsafe items, or assume legal responsibility unknowingly. Do not make the other person responsible for reducing the discomfort that prompted you to write.