How To Brief A Development Agency

WHY THE BRIEF MATTERS MORE THAN THE AGENCY

Founders obsess over choosing the right agency and underinvest in the document the agency works from. That's backwards. A brilliant agency with a bad brief builds the wrong thing efficiently. An average agency with a sharp brief builds the right thing adequately. The brief is the highest-leverage document you'll write this year — it determines the quote you get, the product you receive and whether the relationship survives first contact with reality.

It also protects you commercially. A written brief, referenced in the contract, is what "done" means. Without it, scope arguments are your word against theirs, and you will lose — or win at the cost of the relationship. Write it down, get it agreed, build from it.

You don't need to be technical. You need to be clear. The seven sections below are everything a good agency needs — nothing more.

1. GOALS: WHAT DOES SUCCESS LOOK LIKE?

Start with the business outcome, not the features. "We need an app" is not a goal. "We need 500 paying users in six months" or "we need to cut our manual booking workload by half" is a goal — and it changes what gets built.

Write down:

• The one business objective this project serves (revenue, users, efficiency, fundraising credibility — pick the real one).
• How you'll measure it. Signups? Transactions? Time saved? If you can't name the metric, you can't tell whether the build worked.
• The problem in one paragraph. Who hurts, how, and what they do today instead of using your product. Agencies that understand the problem make better micro-decisions than agencies working from a feature list.

This section also tells the agency what not to build. A goal of "validate demand fast" argues for a leaner build than "impress Series A investors with polish" — same idea, different product, different price.

2. USERS: WHO IS THIS FOR?

"Everyone" is not a user. Name your first users specifically:

• Who they are — in concrete terms. "Independent gym owners in Manchester with 200–500 members" beats "fitness businesses".
• What they do now — the spreadsheet, the phone calls, the competitor product they'll compare you against.
• What devices they use — a tradesperson booking jobs from a van needs mobile-first; an office manager needs desktop. This single answer shapes the entire build.
• How many of them, when — 50 beta users is a different architecture conversation than 50,000 on launch day. Be honest; overestimating scale is how MVPs get over-engineered.

If you've done customer interviews, attach the notes or a summary. Real user quotes in a brief are worth more than ten pages of requirements — they keep every decision anchored to a human being.

3. SCOPE: MUST-HAVE VS NICE-TO-HAVE

This is where briefs live or die. List every feature you can think of, then force-rank ruthlessly:

• Must-have (v1): the product is pointless without these. Aim for three to five. If everything is must-have, nothing is — and the agency can't price it.
• Nice-to-have (later): genuinely valuable, but the product works and the business learns without them. Park them in a phase 2 list so they don't inflate the v1 quote.
• Explicitly out of scope: the things you've decided not to build. Writing "no native mobile app in v1 — responsive web only" prevents the most expensive misunderstandings.

For each must-have, write one sentence describing what the user does, not how the system works: "A customer books a class in under a minute from their phone" — not "implement a booking microservice with Redis caching". You're briefing the outcome; the agency owns the how. (Our MVP scoping guide walks through cutting v1 to the bone.)

Also note integrations: payments (Stripe?), email, CRM, accounting, maps — anything the product must talk to. Integrations are where hidden complexity lives, so name them early. If you're unsure whether you need CRM development or just a simple contact flow, say so — a good agency will advise.

4. BUDGET: BE HONEST ABOUT THE RANGE

The most common briefing mistake: hiding the budget "so they don't just quote that number". Here's what actually happens when you hide it. The agency guesses — usually high, to cover the unknowns — and you get a quote for a £60k build when you had £20k. Everyone's time is wasted, including yours.

Stating a range doesn't mean you'll pay the top of it. It means the agency designs a solution that fits: "£15k–£25k" gets you a scoped proposal with options at both ends, trade-offs explained, and a phase 2 for the rest. No range gets you a guess.

Indicative UK bands to calibrate against (not quotes): marketing site £3k–£8k, web app MVP £15k–£60k, mobile app £25k–£80k+. If your range sits below what the work needs, an honest agency will tell you — and tell you what the range does buy. That's a useful conversation; a fantasy quote is not.

Also state how you want to pay: fixed price against milestones (best for defined scope), or time-and-materials (best when scope will evolve). Each has honest uses; the brief should say which you prefer and why.

5. TIMELINE: DATES AND DEPENDENCIES

Give the agency your real dates — including the embarrassing ones:

• Launch target and why. "Demo day, 14 June" lets the agency plan backwards and tell you what's achievable. "ASAP" tells them nothing.
• Your availability. You'll need to review designs, answer questions and test builds — typically a few hours a week. If you're unavailable for three weeks in August, say so now, not when the project stalls.
• Dependencies outside the build. Content you must supply, a third party's API, app store review times (add 1–2 weeks for iOS), a rebrand landing in May. Dependencies kill timelines more often than coding does.

A word on speed: 8–16 weeks is typical for a web app MVP once kicked off. If your timeline is shorter than the work allows, say so — the agency can propose a phased launch (core for the deadline, rest after) rather than everyone pretending.

THE BRIEF TEMPLATE CHECKLIST

Copy this, fill it in, send it. One to two pages is plenty — clarity beats length.

Two more things that strengthen any brief. Reference designs you like — not to copy, but to calibrate taste; "like this onboarding flow" communicates more than a paragraph. And name your decision-maker and date — agencies prioritise enquiries that will actually decide, and you'll get sharper attention.

Before you send it anywhere, sanity-check the brief against whether you're ready for an agency at all — and if the answer is yes, send it to us. Founders who brief like this get our best work; it's that simple.

BRIEFING AN AGENCY — FAQs