Web Design Brief: What To Include So Agencies Deliver
A weak web design brief is the single biggest reason projects drift, budgets bloat, and launches slip. Not a difficult client. Not a slow agency. The brief. Get it right upfront and everything downstream, from the first wireframe to the final sign-off, moves faster and costs less. This guide walks through exactly what to include so an agency has everything they need to build the site you actually want, not the site they had to guess at.
On this page
Start With the Business Problem, Not the Design
Most clients open with aesthetics. ‘We want something modern, clean, and professional.’ That tells an agency almost nothing useful. Start instead with the problem the site needs to solve.
‘We lose roughly 60% of visitors on the contact page and we do not know why’ is a brief. It gives an agency a target. They can look at form friction, page load speed, and trust signals. A vague stylistic request produces a site that looks fine and performs badly.
Write one clear sentence about what is broken or missing today, and one sentence about what good looks like. Everything else in the brief follows from that.
Define Your Audience With Specifics, Not Generalities
Vague audience descriptions produce vague designs. ‘Small business owners aged 30 to 50’ could describe half the population. Push yourself to describe one real person instead.
For example, ‘a sole trader electrician, no office staff, checking their phone between jobs, needing to book a quote in under two minutes’ gives a designer something concrete to work with. Navigation depth, button size, form length, and page speed decisions all shift when the audience is that specific. One real person beats five broad personas every time.
List Every Function the Site Must Perform
This is the section most briefs skip, and it is the most common cause of post-launch scope creep. Write down every single thing the site needs to do.
Cover the obvious and the less obvious. A CMS for blog updates, a contact form, a booking tool, an e-commerce checkout, a member login area, a live chat widget, a newsletter signup that feeds into your email platform, any e-commerce structural requirements you know about upfront. If you run any automations, name the tools. Missing one integration at briefing stage typically adds days of development time and a change-order conversation you did not want.
Share Examples of Sites You Like and Why
Reference sites do not box a designer in. They anchor a taste conversation in fact rather than opinion. Pick two or three sites, include the URL, and write one sentence on what specifically works.
For example, ‘the checkout on this site uses a single scrolling page rather than multiple steps and it feels faster’ is useful. ‘This site looks nice’ is not. The ‘why’ is the whole point. It tells a designer what you value, whether that is clarity, speed, a specific navigation pattern, or a tone of voice. Without it, design feedback rounds multiply.
Be Explicit About Budget and Timeline
Hiding your budget does not protect you. It produces a quote built on guesswork. An agency will size a project to fit the money available, so give them a range.
Say ‘we have between £4,000 and £6,000 and a firm go-live date tied to a product launch in ten weeks.’ That lets an agency scope what is genuinely achievable. If your expectations do not match your budget, better to find that out before work starts. A realistic timeline also means agreeing on what happens if content arrives late, which it almost always does.
If you are still weighing up which type of agency to use, this breakdown of what to actually look for in a web design agency covers the key differences worth knowing before you commit.
Spell Out What Success Looks Like
A project without measurable outcomes has no finish line. Both sides end up disagreeing on whether the work is done. Define what success looks like in concrete terms before a single wireframe is drawn.
That might be a target contact form conversion rate, a Google PageSpeed score above 90, a bounce rate below 50% on the homepage, or a specific traffic milestone within three months of launch. If you want a fast site, it is worth understanding what PageSpeed scores actually measure so your target is grounded in something meaningful. Vague success criteria lead to vague delivery.
Decide Who Owns Each Decision Before Work Starts
Unclear ownership is the number one reason timelines slip. Name the one person internally who gives final sign-off on design decisions. Not a committee. One person.
Confirm who is responsible for supplying copy, images, and any existing brand assets. Agree how many rounds of feedback are included and what format they come in. These are not bureaucratic details. They are the difference between a ten-week build and a six-month one. Set the rules of engagement in the brief itself, not in week four when it has already gone sideways.