How to write a brief that gets you a good agency proposal

Most agency briefs we receive are vague — and then the founder is surprised when the proposal that comes back is also vague. The proposal can only be as specific as the brief. Bad inputs, bad outputs.

A good brief does three things at once: it scopes the work, it qualifies the agency (good ones will engage; bad ones will dodge), and it pre-aligns expectations before the contract is signed. Done right, a 1-page brief saves 4-6 weeks of back-and-forth.

Here’s the structure we’d use if we were on the buying side.

What a good brief contains

A complete brief has eight sections. Skip any and the agency will guess — which usually means inflate.

1. The business in 3 sentences

Not your marketing copy. The honest version. “We sell X to Y customers; we make money by Z; we’re [stage] and growing [rate].”

If you can’t write this in three sentences, the brief problem is downstream of a positioning problem. Fix that first.

2. The specific work you want done

“Marketing services” is not work. “Build a marketing site, run paid Google search, write 4 blog posts a month for 6 months” is work.

The more specific you can be, the more specific the proposal will be. If you’re not sure exactly what you need, write down the outcome — “land 10 qualified demos a month” — and let the agency propose the scope.

3. What success looks like

Define the metric. Not “grow the business” — “increase qualified demo bookings from 12/month to 25/month by Q4.”

Two things this filters out:

Agencies that won’t commit to outcomes
Engagements where you and the agency have different definitions of success

4. Constraints

Budget range, timeline, must-haves, must-nots.

Budget range. Yes, share it. Telling an agency “show us pricing options across budgets” gets you vague proposals. Telling them “we have $X/month and want to know what we can do with it” gets you a specific plan. The fear of being upsold is real but solved by working with agencies who won’t, not by hiding the budget.

Timeline. When does this need to start? When does the first measurable outcome need to land?

Must-haves. Existing tech, integrations, brand guidelines, compliance requirements.

Must-nots. Specific channels you’ve ruled out, things that have failed before, hard limits.

5. What’s been tried

What you’ve done in this space already. What worked. What didn’t. Honestly.

This section sounds optional but it’s the most valuable. It tells the agency the second-time-around context that’s invisible from outside. Without it they’ll often propose what you’ve already tried.

6. Internal team and roles

Who will work with the agency from your side? Who has decision authority? Who reviews work? Who pays the bills?

If you don’t have someone who can review and approve work, an agency engagement will stall. Better to know upfront.

7. Process expectations

How do you want to work? Weekly calls? Slack channel? Async-only? Monthly reports?

Agencies have defaults; sometimes they fit and sometimes they don’t. Specifying upfront avoids the conversation in week 6 about why nobody’s responding to your DMs.

8. What happens after

Who owns the work product? What’s the off-boarding plan? What contract length are you proposing?

This section discriminates harder than any other. Good agencies have clean answers. Bad agencies dodge.

What to leave out

A few things agencies don’t need in the brief — and that bloat the document if included:

Your founding story. They’ll ask if they need it.
A 20-page brand guidelines doc. Link to it; don’t embed it.
Your competitive analysis. They’ll do their own.
All your historical performance data. Summary numbers are fine; raw exports overwhelm.
Your design preferences for the website you haven’t asked them to design yet. Stay on the work, not aesthetic taste.

The budget conversation

The most asked question: “Should I share budget in the brief?”

Yes. Three reasons:

Filters bad-fit agencies fast. If your budget is $3k/month and they typically work with $50k clients, you’ll find out in their reply, not 6 weeks into a misaligned engagement.
Calibrates the proposal. Without budget, agencies have two choices: propose maximum scope (you’ll panic) or propose minimum scope (you’ll wonder what they could have done with more). Neither is useful.
Removes the dance. The pricing conversation will happen. Pre-empting it saves everyone time.

The only argument for hiding budget is fear of being charged the full amount you disclose. Solve that by working with agencies who won’t, not by hiding numbers.

Red flags in agency responses

When proposals come back, what to watch for:

Generic case studies. Real responses cite work relevant to your situation. Stock case study decks suggest they didn’t read your brief.
No specific questions about your business. Good agencies ask 5-10 questions before quoting. Templates don’t ask anything.
Pricing that doesn’t match scope. A proposal that quotes $5k/month for what your brief specified as $30k of work is either underscoping or going to scope-cut later.
Vague timelines. “We’ll deliver in Q3” is not a timeline. “Discovery weeks 1-2, design weeks 3-5, launch by week 8” is.
No mention of how they’d measure success. If they don’t propose metrics, they don’t plan to be held to any.
Long contracts with no early-exit. Healthy retainers are month-to-month after a brief commitment. 12-month no-exit contracts protect the agency, not you.

The 1-page version

If you want a brief in under 30 minutes, fill in this:

COMPANY: [3 sentences — what you do, who for, current stage]

WORK NEEDED: [the specific services or outcomes]

SUCCESS METRIC: [the number that will define whether this worked]

BUDGET: [range, monthly or one-time]

TIMELINE: [start date, first milestone date, end if applicable]

INTERNAL OWNER: [name, role, decision authority]

WHAT WE'VE TRIED: [previous attempts and outcomes]

WHAT TO AVOID: [tactics, vendors, or approaches that didn't work]

CONTACT: [name, email, phone, response timeframe]

That’s it. Nine sections, one page. Three to five hours total to think through, and the proposals back will be 10x tighter than they would have been without it.

The hidden benefit

A well-written brief doesn’t just produce better proposals — it also produces a better engagement once the contract is signed. The same document that scopes the work becomes the alignment document that the team works against in month one.

Most stalled agency engagements stall in month two because the agency and the client interpret the original ask differently. A brief that pre-emps that conversation is worth its weight in invoice disputes avoided.

One last note

The best test of a brief: would another agency, reading only this document and never having spoken to you, be able to scope the work the same way as you? If yes, you’ve written a good brief. If no, the missing details are the same details that’ll cause friction in the engagement. Add them.