AI-written briefs are longer than ever. And worse

You know the type. A brief lands in your inbox. It's long, neatly formatted, full of words like “holistic” and “customer journey.” And after the third read you still can't say what the campaign is supposed to achieve.

That's what agency leaders talked about this week at Digiday's Media Buying Summit. Nadja Bellan-White, North America CEO of M&C Saatchi, estimated that around 85% of the briefs her agency receives are written with AI tools. Her verdict: “a little bit ridiculous.” Another agency executive called some recent briefs the worst of their career, because they simply don't state a marketing goal. Tony Russo of the agency Mile Marker framed it as a judgment problem: people have outsourced their thinking to AI.

The data backs it up. In a Basis Technologies survey (July/August 2026), 56.4% of marketers and agencies said they use AI to build strategy, media or creative briefs.

A brief was never a document. It was a decision

Anyone who has managed agencies long enough knows this: a good brief is short because someone made a call before writing it. One problem. One audience. One single-minded proposition, the single thought the campaign has to sell. Everything else is context.

AI is brilliant at context. It fills gaps, rounds things off, adds three more audience nuances and two more channels. What it can't do is cut for you. So the AI brief looks more complete than any brief before it, and contains less decision.

Who pays the bill

Here's the part almost nobody mentions. The time marketing saves writing the brief doesn't disappear. It moves to the agency, which has to read, interpret, ask questions and re-brief. Often it ends up having AI summarize the twelve pages. Now an AI is talking to an AI, and the actual objective got lost somewhere in between.

The client still pays for it. In agency hours, in revision loops, in campaigns optimized for something that was never the goal. To me, that makes the brief the one marketing task you shouldn't delegate to AI. Not because AI writes badly, but because strategy is about what you leave out.

The catch

These are views from US agencies at an industry event, and the 85% is an estimate, not a measurement. AI can help with briefs, too: as a sparring partner that spots gaps, or as an editor that cuts. The problem isn't the tool. It's the order of operations.

What I'd do now

• Think first, prompt second. Write the goal, the audience and the one core idea yourself, in three sentences. Only then ask the AI: what's missing, what contradicts itself?
• One page, hard limit. If you can't get the brief onto one page, you haven't decided yet.
• Let the agency grade it. After every brief, one quick question back: is the objective clear, yes or no? Five minutes that save a re-brief.

Bottom line: AI can make your brief longer. Making it clearer is still your job.