If three quotes for the same website come back at £900, £2,400 and £11,000, the problem is usually the brief, not the agencies. They've each priced a different job because the brief let them. Nine pieces of information fix that. It takes an hour to write and it's the highest-value hour in the whole project.
1. What the site is for
One sentence, and be concrete. "Get plumbing enquiries from homeowners in three postcodes" is a brief. "Modernise our online presence" is a mood. The first can be designed for and measured; the second can't be either.
2. Who it's talking to
The actual customer. Trade or public, national or local, buying on price or on trust. A site selling to procurement managers looks nothing like one selling to homeowners, and getting this wrong wastes the whole budget.
3. How many pages, roughly
List them. Home, about, three services, contact, blog — that's eight and everyone can price it. "A website" could be five pages or fifty.
4. What has to work, not just exist
Contact form, online booking, payments, a members' area, a product catalogue with variants, multi-language. Each of these is a different amount of work. Listing them is the single biggest cause of quotes converging.
5. Who writes the words
You, or them? This changes the price and the timeline more than any design decision, and it's the most commonly skipped line in a brief.
6. Photography and brand
Do you have usable photos and a logo in vector format, or does that need creating? Stock imagery is a fallback, not a plan — a page of obviously bought photographs undercuts the trust the rest of the site is trying to build.
7. Budget range
Say a range. Withholding it doesn't get you a cheaper quote — it gets you three quotes for three different products, none of which you can compare. A designer who knows you have £2,000 will tell you honestly whether your list fits in it. That conversation is worth having before the design starts.
8. Deadline, and whether it's real
A trade show, a lease start, a funding round — real deadlines change how a project is run. "Ideally soon" doesn't. Say which yours is.
9. Who decides
Name them. Projects with an unnamed approver run late every time, because the person with the opinion appears in week six.
What you don't need to include
Which platform to use, what colours you like, or how the navigation should work. Those are answers, and you're buying answers. Briefs that specify the solution get you a supplier rather than a designer — and if you already know exactly what to build, you're paying agency rates for typing.