Choose the right purpose for the message
Decide whether the message is meant to inform, apologize, ask, support, or close a practical loop. For a message about how to ask a coworker to stop interrupting you, use this factual base: use recent examples, observable impact, and the work requirement rather than labels about personality.
Use detail that helps a decision
Include the smallest set of details that lets the recipient understand the impact and choose a response. Ask for a specific change, decision, or working agreement and choose a time to review it. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Know what the message cannot achieve
Do not diagnose, gossip, embarrass a colleague, or turn one incident into a judgment about their character. Move harassment, discrimination, threats, health risk, and retaliation into the appropriate protected process. The message can offer clarity, but it cannot guarantee forgiveness, agreement, attention, or renewed contact.