The rotation flips at 18:00. The outgoing note is a link to the channel and "pretty quiet, shout if anything looks weird." At 03:10 the incoming person is paging through two hundred messages to find out whether the restart at 01:40 worked.
It had not. Someone had already said so. The sentence was in the middle of a thread about something else.
An on-call handoff is a project handoff compressed into the hour before you stop being responsible. Reasons still matter more than state. The incoming person can find the dashboards. They cannot find the thing you already know is a dead end.
Three facts above the scroll
Write these before any paste of the channel.
What is on fire. Present tense, one sentence each. "Checkout 5xx on the EU region since 16:20 UTC. Customers can browse; they cannot pay." Not "some errors, looking into it."
What is only being watched. The elevated latency you have not paged on. The vendor incident you are treating as background. Naming the watch list stops the next person from declaring a second incident you already triaged.
What was tried. Each attempt, the time, and what it ruled out. "Restarted the payment worker at 17:05 UTC. Error rate unchanged. Not a stuck process." Three lines is usually enough. If an attempt ruled nothing out, say that — it still saves an hour.
The channel can remain for anyone who wants the noise. The point is that acting does not require reading it.
Separate what you saw from what you concluded
"The vendor is lying about their rollback" is a conclusion. "Their status page says rolled back; we still see the old header" is what you saw. The incoming person will page a vendor differently depending on which one you wrote.
Put the premise on its own line. Mark guesses. An assistant that sat with you through the afternoon will happily promote a hunch into a fact. You are the one who sends the package, so you are the one who keeps the label honest.
Customer wording belongs in quotes, with a time. Paraphrase drops the sentence they will hold you to. That is the same failure as a customer escalation that loses the ask.
Name the open decision and who owns it now
"Open: whether we disable the new tax path in EU overnight. I have been holding it. It is yours from 18:00 UTC. I would disable it."
Without that sentence the incoming person monitors. Monitoring is how a quiet night becomes a morning incident. Transfer the work and the authority together. "Let me know if you need anything" transfers neither.
Send it before you close the laptop
Have the assistant draft from the session if that is where you worked the incident. Then read the rendered briefing — the thing they will open at 03:10 — and approve it. If they have an account, you need an accepted contact. If they do not, they get email and a page.
No attachments. Link the runbook. Link the graph. Put the three facts in the brief.
If you are about to drop the pager, connect your assistant and have it list what you already tried while you can still remember the times.