How to brief an agency so the proposals are comparable

Aug 22
3 min read

Updated: 3 days ago

Introduction

Send a vague brief to three suppliers and you receive three proposals for different work at different prices, none of which can be compared with the others.

The brief is the buyer's main instrument of control, and writing it well takes an afternoon. Writing it badly costs considerably more than that later.

1. How to brief an agency: state the problem, not the solution

The most common mistake is briefing an output rather than an outcome.

"We need a new website" is a solution you have already chosen. "Enquiries have fallen by a third and we do not know why" is a problem, and it invites proposals that might identify a faster fix.

Suppliers who only do one thing will propose that thing regardless. A problem-led brief exposes that immediately, which is useful information about who you are talking to.

2. Disclose the numbers

Withholding your figures produces generic proposals, and it is the most self-defeating habit in this process.

Share what you can: monthly enquiry volume, conversion rate, average transaction value, current spend by channel, what a customer is worth. Under an agreement if necessary.

A supplier who knows a customer is worth several thousand will propose different work than one guessing at a few hundred. Vague briefs produce vague proposals and then surprise at the price.

3. Say what you have tried and what happened

Prevents repetition and reveals competence.

List the channels tried, roughly what was spent, and the outcome. Include the things that did not work and your view of why.

Suppliers who ask thoughtful follow-up questions about this section are the ones engaging with your actual business. Those who ignore it will propose the thing that failed last year.

4. State the constraints honestly

Constraints are the part buyers hide and the part suppliers most need.

The budget range, the timeframe, who will do the work internally and how much time they have, what tools you already pay for, brand or regulatory limits, and anything that is not negotiable.

Concealing the budget wastes everyone's time — you receive proposals at the wrong scale and then negotiate downward, which usually means the same price for less work described differently.

5. Define what a successful engagement produces

Say what you expect to exist at the end, and how it will be judged.

Deliverables listed as things: a working measurement setup, a defined follow-up sequence, documented procedures, a trained team, a specified number of assets. Plus the metric and the review date.

This is also where to state ownership. Ask that accounts, data and files are owned by your business and transfer on completion, and make it a condition of the brief rather than a negotiation at the end.

6. Ask for the same structure from everyone

Comparability requires imposing a format.

Ask each supplier for: their reading of the problem, the approach, an itemised list of deliverables with dates, the total cost broken down, who will actually do the work, what they need from you, and how it will be measured.

Without this, comparison becomes a judgement about presentation quality. With it, the differences in substance are visible immediately.

7. Ask them to tell you what is wrong with your brief

The most valuable question in the process, and rarely asked.

Invite each supplier to challenge your framing: what have we misdiagnosed, what would you do differently, what would you not do at all.

Suppliers willing to disagree with a prospective client during a sale are demonstrating something worth buying. Those who agree with everything are selling agreement, and the disagreement will arrive later at a worse moment.

8. Keep the brief to two pages, and send the same one to everyone

Length works against you. Two pages gets read carefully; twelve gets skimmed and answered from a template.

Send an identical brief to each supplier, with identical deadlines, and answer questions in a way that shares the answers with all of them. Otherwise you are comparing proposals written with different information.

Keep the brief afterwards. It becomes the reference point for whether the work delivered matches what was asked for, which is a question that gets asked around month four surprisingly often.

Conclusion

Brief the problem rather than the solution, disclose your real numbers, and say what you have already tried and why it failed.

State budget, timing and internal capacity honestly, define the deliverables and ownership you expect, impose a common proposal structure so responses are comparable, invite suppliers to challenge your framing, and keep it to two identical pages sent to everyone.