They ship. They join the calls they are invited to. They do not hear the ten minutes after the meeting, and they do not see the emoji thread where the deadline actually moved. The note you send them as if they were in the building will miss the only facts they cannot recover.
Write to a contractor the way you write to a cold reader who happens to be good at the work.
Put the hallway in the brief
What is decided. What looks like a mistake on purpose. Who they ask for which thing. The date that is real, not the date someone said in passing.
If you are asking them for a decision — a cut, a date, a yes on a change — close the list and give a recommendation. Freelance client communication has the same failure mode in the other direction: an open "whatever you think" leaves the contractor owning a choice they were never authorised to make. Do not do that to them, and do not do it to yourself.
Label assumptions. They cannot walk over and check.
They may not share your tools, and they do not have to
You do not need them on Slack to send a briefing. You do not need them on the same assistant. They connect Claude or ChatGPT if they want; they can also reply from the page after an email.
If they have never activated an account, the send is email. Receiving is free. Nothing to install. If they sign in later with an emailed code, invite them as a contact before you start a new thread. The one they already answered can continue. You cannot accept your own request.
There are no attachments. Point at the repo and the spec. A zip of context is how they spend a billable hour unpacking your filing system.
Approve the words they will bill against
A contractor will treat a sentence under your name as scope. You review the package. An assistant can draft. It cannot take the commitment for you.
Use the name on the statement of work. A private nickname — the one that made sense in your contact list — is not how they should see themselves in a brief they might forward to their own client.
If they are already in a session as "the contractor," connect your assistant and have it rewrite the note as if that person had missed every meeting this week. They did, even if they were on the invite.