How to Write a Google Ads Brief Your Agency Will Follow

A vague or incomplete Google Ads brief is one of the most common reasons agency campaigns underperform from the start. When the brief does not answer the questions that matter – what success looks like, who the customer is, what the competition charges, how the sales process works – the agency fills the gaps with assumptions. Sometimes those assumptions are right. Often they are not. A well-written Google Ads brief sets up your agency for success from day one and gives you a clear basis for evaluating their performance throughout the engagement.

What a Google Ads Brief Is Not

A Google Ads brief is not a list of keywords you want to target. It is not a creative mood board. It is not a request to “get us more leads” with a vague monthly budget attached. These inputs give an agency almost nothing to work with strategically. The brief is a document that answers every question the agency would otherwise have to guess at.

Business and Offer Context

Start with the fundamentals of your business – but specific to the Google Ads context, not a general company overview:

What are you selling, and to whom? Be specific about the product or service, the price point, and who the ideal customer is. “We sell cloud software to mid-size logistics companies with 50-200 employees, priced at $800/month” is useful. “We sell software solutions” is not.
What is the lifetime value of a new customer? This determines how much the agency can justify spending to acquire one. Without it, they cannot set meaningful CPA targets.
What is your close rate from lead to sale? If only 10% of leads convert to customers, the cost per lead target needs to account for the 90% that will not convert.
What makes you different from competitors? The agency needs to write ad copy that positions you correctly. List your key differentiators, the objections customers raise, and how you typically address them.

Campaign Goals and Success Metrics

The most important section of a Google Ads brief is a clear, quantified definition of success. Avoid goals like “increase leads” or “improve ROAS.” Write goals like these instead:

Target cost per lead: $60 maximum, with volume of 50+ leads per month
Target ROAS: 3.5x on purchase conversions with a minimum of $20,000 monthly ad spend
Target CPA: $150 for new customer acquisition, with a 30-day attribution window

If you do not know your target CPA or ROAS, work backward from your margins. What is the maximum you can pay to acquire a customer while remaining profitable? That is your upper bound. Understanding what counts as a good ROAS in your category will help you set a realistic expectation rather than a number that sounds good but is impossible to hit.

Budget and Spend Expectations

Your Google Ads brief should include not just a total budget but a spending rationale:

Total monthly ad spend (not inclusive of agency fees)
Whether there are seasonal peaks or troughs where budget should be adjusted
Whether you want a ramp period (starting at a lower budget before scaling) or a full launch from month one
Any categories or keywords you want to exclude from spend

Knowing what good performance looks like from your agency is easier when you have agreed on these numbers upfront – because then there is no ambiguity about whether the targets were realistic.

Target Audience and Customer Journey

Describe your customer with enough detail that the agency can make targeting decisions without guessing:

Geography – specific regions, cities, or radius targeting if relevant
Device preferences – if your customers overwhelmingly use mobile or desktop, say so
Decision timeline – how long does the average customer take from first contact to purchase?
The common objections – what stops people from buying, and how do they usually get resolved?

Our guide to fixing Google Ads performance explains the most common causes of Google Ads underperformance – which are often rooted in brief-stage gaps that no amount of campaign optimisation can fix after the fact.

Competitive and Market Context

Your agency needs to understand the competitive landscape to write effective ad copy and set sensible bid expectations:

Name your top three to five direct competitors and what they offer
Share any market intelligence you have on how they position their offers
Identify keywords you know are highly competitive (or expensive) in your space
Flag any industry regulations that affect what can be said in ad copy

Access and Asset Requirements

A Google Ads brief should include a list of what you will provide and what you need the agency to supply: Google describes how agencies work across client accounts on its page About Google Ads manager accounts.

Google Ads account access – are you sharing access to an existing account, or starting fresh?
Landing pages – are they already built, or does the agency need to create or recommend them?
Brand guidelines – logo, colours, tone of voice requirements for ad copy
Conversion tracking – is it already set up, or does the agency need to implement it?

Conclusion

A strong Google Ads brief is the difference between a campaign that starts with a strategic foundation and one that starts with guesswork. Include your offer context, clear performance targets, a realistic budget with rationale, an honest picture of your customer, and the competitive context your agency needs to write copy that stands out. The hour you invest in writing a thorough brief saves weeks of back-and-forth and misaligned expectations once the campaign goes live.

Frequently Asked Questions

How long should a Google Ads brief be?

Long enough to answer the questions an agency would otherwise guess at, which is often two to four pages. Clear numbers and specific details matter more than length.

What if I do not know my target CPA or ROAS?

Work backward from your margins and your lead-to-sale rate, and share those figures. The agency can then propose realistic targets. Our guide to how much to spend on Google Ads helps you size the budget to match.

Should I include account access in the brief?

Yes. State whether there is an existing account and who owns it, and make sure you keep ownership of your own account. Our post on the hidden costs of running ads in-house vs hiring an agency covers what to weigh before you hand work over.

Want expert help with your Google Ads? See our Google Ads management service.