An expert can usually answer a question in their field in about ninety seconds. What costs them an hour is working out what the question is about — which project, which constraints, what you already tried, and which of the four things you mentioned is the one you need decided.
A context brief is the passage that removes that hour.
The definition
A context brief is a short passage — roughly 150 to 400 words — written to give a reader with none of your history enough background to answer one specific question, and nothing beyond it.
Two constraints carry the definition, and dropping either changes the object.
The reader is cold: not uninformed in general, but holding none of your particular history. No memory of the meeting, no idea which of your three systems you mean, no sense of what you already ruled out. That is what forces you to expand the acronym and name the thing you have been calling "the newer one" for a month.
The scope is one question. A context brief is indexed to a specific ask, and that anchor is what lets it end. Without it the passage grows to cover everything a reader might conceivably want, which is how a two-paragraph note becomes a nine-page document nobody opens.
The length range follows. Under about 150 words you force the reader to guess at something you left out, and a guess is how you get a confident answer to a question you did not ask. Past about 400 the setup buries the ask.
Three things it is not
Not a summary
A summary compresses what happened: faithful to its source and roughly proportional to it.
A context brief selects. It is judged only by whether the reader can now answer the question, not by whether it represents the material fairly. A summary of a six-week project mentions the six weeks; a context brief may skip five of them without apology, because they do not bear on the choice in front of the reader. It is deliberately unfaithful to the source and strictly faithful to the question.
Not an executive summary
An executive summary leads with the conclusion, so a reader who stops after the first paragraph still gets the point.
A context brief does the opposite: it supplies the premises and withholds the conclusion, because the reader's own judgment is the thing being requested. Open with your answer and you have anchored the person whose independent read you asked for. An executive summary is for someone who will probably accept your read; a context brief is for someone whose read you want.
Not documentation
Documentation is durable, general, and maintained — written once for many readers over a long period.
A context brief is disposable and single-use. It is correct for one person at one moment, and nobody should ever update it. Confusing the two costs you both ways: promote a context brief into documentation and you get a stale page; send a documentation link instead of one and you have handed the reader a pile of material plus the job of selecting from it, which was your job.
What makes one good
Three tests, in the order they tend to fail.
It assumes nothing. Every proper noun is introduced, every acronym expanded on first use. The test is not "would they probably know this" but "does the passage still work if they do not." Shorthand is the most common defect because it is invisible from the inside — you cannot hear your own jargon.
It stops at the boundary of the question. Everything upstream of the ask, nothing downstream. The usual overrun is narrative: the sequence of events that led here. That sequence is real, and it is almost always the writer's material rather than the reader's. A sentence whose actual purpose is establishing that you are not at fault belongs somewhere else.
It reads cold in under two minutes. Read it back as the recipient, pretending you know nothing. Every place you stall is a repair. Two minutes is roughly the budget a busy person gives an unexpected request before deciding to engage now or later — and later is where requests die.
One habit is worth the two words it costs: mark what you know apart from what you assume, because a reader weighs a confirmed constraint differently from a guess.
The artifact is older than AI
None of this is software. The context brief gets reinvented under a dozen names by anyone whose job involves handing a problem to someone who was not there.
Briefing books prepare an official to walk into a meeting on a subject they have never handled. Case memos bring a colleague up to speed on a matter they are taking over. Handover notes exist because the person leaving a role knows forty things that live nowhere else. Same object every time: a bounded, disposable passage that makes a cold reader competent for exactly one occasion.
These have always been expensive to write and cheap to read. That asymmetry is why they get written mainly when the reader outranks the writer, and why most people asking a peer for help send a link and an apology instead. A model that sat through the working session changes the economics of the first draft, not the responsibility for it. Selection is judgment, and judgment is what the reader is trusting when they answer.
Its role inside a briefing
In a RelayLink briefing, the context brief is one named field among several — it sits alongside the ask, the assumptions, the options considered, and the sender's note. Your assistant drafts it from a private session that never leaves your side, and you review the rendered package before anything sends.
The neighbouring fields carry the labelling. Assumptions are marked stated by sender or inferred by sender's AI, so the reader can separate what you know from what a model concluded about you. The context brief supplies the ground; the labels say how firm each patch of it is. The rest of the vocabulary sits in the correspondence glossary, and the reason the field has to exist at all is that context does not transfer between assistants on its own.
The artifact stands without any of that, which is the useful part. Write one by hand at the top of your next request for help — 150 to 400 words, no acronyms, no history, ending at the question — and watch how much shorter the reply thread gets. If you would rather have the first draft assembled from the session where you already worked the problem out, connect your assistant.