A good developer brief explains what problem you're solving, who it's for, what success looks like, and what constraints you're working within. That's it. The brief doesn't need to specify how the software should be built — that's the developer's job — but it does need to give them enough context that they can ask the right questions, scope accurately, and tell you honestly whether they're the right fit. Most briefs fail because they skip the problem entirely and jump straight to a list of features.
Why Most Briefs Go Wrong Before the Work Starts
The single most common mistake founders make when briefing a developer is describing a solution rather than a problem. "I need a web app where users can log in, create profiles, and message each other" tells a developer what to build but not why. Without the why, they can't push back sensibly, they can't suggest a simpler path, and they're quoting in the dark. The result is either a ballooning scope or a product that technically works but solves the wrong thing.
The second mistake is treating the brief as a formality. Founders who say "I'll explain it on the call" often discover, two calls in, that what seemed clear in their head is genuinely ambiguous when someone else tries to build it. A written brief forces clarity. The act of writing it is half the value.
What a Strong Developer Brief Includes
You don't need a 40-page specification. A well-structured one to two page document covering the following is enough to get a meaningful first conversation with any competent developer or consultancy.
- The problem you're solving — in plain English, for a specific person. Not "businesses want better workflows" but "our account managers currently track client renewals in a shared spreadsheet and things fall through the gaps every quarter."
- Who the users are — be specific. Internal staff only? Customers aged 35–60 who are not especially tech-savvy? A handful of power users who'll use it every day? User type shapes every decision downstream.
- What success looks like — a concrete outcome, not a vibe. "Renewal reminders go out automatically and no account falls through without a logged action." That's testable.
- What already exists — current tools, systems, or workarounds. If you're using Airtable, HubSpot, or a custom legacy system, say so. Integrations are often where scope quietly doubles.
- What's out of scope — just as important as what's in. If you don't want a mobile app yet, say so. If reporting dashboards are a phase two, flag it now.
- Timeline and budget range — even a rough bracket ("we'd like something live within three months" or "we have a budget in the region of £15–25k") helps a developer tell you quickly whether a conversation is worth having for both parties.
- How you'll measure it — what does good look like six months in? Fewer support tickets? More conversions? A specific manual process eliminated entirely?
You don't need to know the tech stack, the architecture, or even whether it should be a web app or a mobile app. Those are questions worth asking together. What you do need to know is the problem, the user, and the outcome. Everything else is negotiable.
How to Write the Brief, Step by Step
- Start with the problem, not the product. Write one to two sentences describing what's currently broken, slow, or missing. Pretend you're explaining it to a smart friend who works in a completely different industry.
- Describe the user concisely. Name the person who will actually use this thing. Their role, their technical comfort level, and roughly how often they'd interact with it.
- Write out the core user journey in plain language. Not a wireframe — just sentences. "A manager logs in, sees which clients are due for renewal this month, clicks through to a client record, and adds a note." That's enough to be useful.
- List your existing systems. Any tool you're already paying for that this new thing might need to talk to belongs in the brief. CRM, payment processor, email platform, internal database — list them all, even if you're not sure they're relevant.
- State your constraints honestly. Budget, timeline, team size (will anyone internal be maintaining this?), and any hard technical requirements that are already decided.
- Describe what done looks like. Write a sentence or two about what will be true when the project is a success. This is the clearest signal to a developer about whether they're the right fit.
- Add any context about previous attempts. If you've tried to build this before, or had a bad experience with another agency, say so. It saves everyone time and sets the right tone for the relationship.
What to Expect Back From a Good Developer or Consultancy
A decent developer or consultancy won't just quote against your brief — they'll interrogate it. Expect questions about edge cases you haven't considered, pushback on assumptions that affect scope, and possibly a suggestion that what you actually need is simpler (or more complex) than what you've described. That conversation is a good sign, not a difficult one.
What you should be wary of: anyone who reads your brief, asks no meaningful questions, and sends a quote within 24 hours. Building software against an incomplete understanding is how projects go sideways. A consultancy worth working with will want to understand the problem before they commit to solving it.
Common Mistakes to Avoid When Briefing a Development Agency
- Treating the brief as a contract. A brief starts a conversation. Scope will evolve, and that's fine — as long as you're both aligned on what drives changes and what they cost.
- Feature-listing without prioritisation. If your brief is a list of 30 features with no indication of which three matter most, you'll get a bloated quote and a project with no clear north star. Prioritise ruthlessly.
- Hiding the budget. Many founders worry that naming a budget means the agency will spend exactly that. The opposite is usually true: knowing the budget helps a good consultancy propose the right scope, not an inflated one.
- Skipping the "what's already there" section. Integrations and legacy systems have a way of multiplying the complexity of a project by two or three times. Surface them early.
- Writing for a technical audience. Your brief doesn't need technical jargon. Plain English is better. If you find yourself writing "RESTful API" or "microservices" when you don't really know what those mean in your context, delete them.
- Not naming a decision-maker. If three people in your organisation will have opinions on the final product, say so in the brief. "Our Head of Operations has final sign-off" avoids scope creep from committee feedback later.
A Note on Briefing for AI-Assisted or Automation-Heavy Projects
If part of what you want to build involves automation, language models, or AI-assisted features, the same principles apply — but with one addition. Be specific about what the automated part needs to handle reliably versus what can afford to be imperfect. A lot of project scope balloons because someone said "and it should use AI to..." without pinning down what accuracy looks like in practice, or what happens when it gets something wrong. That's a product decision, not a technical one, and it belongs in your brief.
If you're evaluating a consultancy for this kind of work, look for someone who asks "what happens when it's wrong?" before they ask "which model should we use?". That's the practitioner instinct. The tooling question is secondary.
A Simple Brief Template You Can Use Now
| Section | What to Write |
|---|---|
| The problem | One to two sentences describing what's broken or missing today |
| The user | Who uses this, how often, and their technical confidence level |
| Core user journey | Three to five sentences describing the main flow in plain English |
| Existing systems | Any tools, platforms, or databases this needs to connect with |
| Constraints | Budget range, timeline, internal maintenance capacity |
| Success criteria | What will be true when this is working well |
| Out of scope | What you're explicitly not asking for in this phase |
| Previous attempts | Any relevant history — what was tried, what broke down |
How long should a developer brief be?
One to two pages is usually enough for an initial brief. You want it to be long enough to give a developer full context on the problem, users, and constraints, but short enough that someone will actually read it carefully. A 10-page document with every possible feature listed tends to produce a wide quote rather than a sharp one.
Do I need to know which technology to use before briefing a developer?
No. In most cases you shouldn't specify the tech stack unless there's a genuine, pre-existing reason — for example, it must integrate with a system that only supports a particular language. Otherwise, leave the technical decisions to the developer. That's what you're paying for. Specifying a stack without a reason can accidentally limit your options or push up the cost.
Should I share my budget in the brief?
Yes. Sharing a budget range (not a hard ceiling) helps a consultancy propose an appropriate scope. Without a budget, developers tend to quote for everything on the list, which is rarely what you need. A rough bracket like "we have somewhere between £10k and £25k for a first version" gives the developer enough to work with and avoids wasting both parties' time.
What's the difference between a brief and a specification?
A brief describes the problem, the users, and the outcomes. A specification describes the solution in technical detail. You typically start with a brief, have a scoping conversation with the developer, and only produce a specification once you've agreed on the approach. Trying to write a full specification before talking to anyone usually produces something that needs to be rewritten anyway.
How do I brief a consultancy if I've never worked with developers before?
Focus on the problem, not the solution. Describe what's currently not working and for whom, give a sense of the outcome you want, and be honest about your constraints. A consultancy worth working with will ask the questions needed to fill in the gaps — your job is to give them enough to get started, not to hand over a complete technical plan.