A good social media brief is a short document that tells the agency who you want to reach, what a sale is worth, what you will and will not say, who approves posts and which numbers decide whether the work continues.
Without one, an agency fills the calendar with what it can produce without you: bank holiday greetings, quote cards and "Happy Monday" graphics. The posts look tidy and say nothing about your business.
This guide gives you a ten-section template, with an example of what each section should contain and how to spot a weak answer. It belongs with our guide to choosing a social media marketing agency in the UK.
Why most social media briefs fail
Most briefs fail because they describe the agency's task and say little about your business. "Manage our Facebook and LinkedIn, three posts a week" is a task. It gives no reason to write anything specific.
The templates that rank for this search have the same weakness. One widely shared template from a social software vendor runs to about 250 words. It covers goals, audience and the activation plan, and mentions approvals only as a label, with no steps or owners. It has no budget fields and nothing on what the agency must not say.
ISBA, the body for UK advertisers, published a best-practice briefing guide in March 2021, which says a good brief saves time, money and headaches. The full guide is behind a member login, and the summary page is open to read.
The ten sections
Write the brief in plain sentences, one to three per section. Two pages is plenty.
| Section | What to write | A weak answer looks like |
|---|---|---|
| 1. Business in one paragraph | What you sell, to whom, in which area | "We are a leading provider of solutions" |
| 2. The goal in money | Enquiries or sales wanted, and what one is worth | "Increase brand awareness" |
| 3. The audience | Job titles or customer types, with the questions they ask | "Everyone aged 25 to 55" |
| 4. What you offer and what you do not | Services you want more of, and ones you do not want to attract | A list of every service |
| 5. Voice and examples | Three posts you like and three you dislike, with reasons | "Professional but friendly" |
| 6. Do not say | Claims, topics, words and competitors that are off limits | Nothing, or "be careful" |
| 7. Approvals | Who signs off, how fast and what happens if they are away | "We will review posts" |
| 8. Access to your people | How the agency gets material from your experts each month | "Send us a brief when you can" |
| 9. Budget and channels | Fee, ad spend if any, and platforms in scope | "Whatever is best" |
| 10. Reporting and review | Numbers that decide continuation, and when you review | "Monthly report" |
Section 1 and 2: the business and the goal
Describe the business as you would to a stranger at a dinner. Then state the goal as a number the business cares about: ten enquiries a month from people in the target market, say, with an average first-year value of a given amount.
If you do not know the number, estimate it and say it is an estimate. A rough goal beats none, because the agency can then judge its own work.
Avoid "increase awareness" unless you can say what awareness would change. Awareness of what, among whom, measured how?
Section 3 and 4: the audience and the offer
Name the people you want to reach and list the questions they ask you most. Customer emails and call notes are the best source.
Say which services you want more of. A firm that would like more recurring work and less one-off work should say so, or the agency will promote whatever is easiest.
Say what you do not want, too. A clinic that does not take emergency work should not attract emergency enquiries.
Section 5 and 6: voice and the do-not-say list
"Friendly but professional" tells an agency nothing. Send three real posts you admire and three you would never publish, and say why.
Then write the do-not-say list. It should include claims you cannot back up, terms your regulator restricts, competitors you will not mention, topics such as politics you will not touch and any phrases you hate.
Regulated businesses need this section most. A law firm has professional rules on how it describes its services and results. A dental practice or clinic has its own rules on claims and patient images. Ask your regulator or compliance lead for the current wording, and put it in the brief.
Section 7: approvals
Approvals cause more friction than any other part of agency work. Name one approver, a backup, a turnaround time and a rule for silence.
A common rule is that posts not approved within two working days are held back, not published. For urgent items, agree a faster route.
Put the approval step before the agency writes a month of posts, not after. Reviewing 12 posts in one sitting is easier than 12 separate requests.
Section 8: access to your people
This is the section most briefs leave out, and the one that fixes the problem in why most agency social content is invisible. Specific posts need a source, and the source is your people.
Agree a monthly 30 to 40 minute call between the agency and the person who knows most about the work. Content repurposing done properly shows how one call becomes a month of material.
If your experts cannot spare 40 minutes a month, tell the agency now. The posts will be more generic and the price should reflect it.
Section 9: budget and channels
State your monthly fee budget and any ad spend separately. Whito, a UK agency that tracks pricing, found a median published social media management price of £358 a month in June 2026, and its May 2026 retainer benchmark puts strategy-led social retainers at £800 to £2,500 a month. Paid social is extra in both. Those are very different products, so say which one you are buying.
Say which channels are in scope. Naming too many spreads the effort. If you are a local service business, Facebook groups and Nextdoor may belong in the plan before Instagram.
Ask for contract terms in the same conversation. Whito notes that 12-month terms are common, that a 12-month commitment can be 10 to 15% cheaper per month, and that a 30-day exit option or performance review clause is worth asking for.
Section 10: reporting and review
Choose the numbers that decide whether the work continues before the work starts. They should be about enquiries and sales, not followers: conversations started, enquiries that mention social media, and cost per enquiry if there is ad spend.
Agree a review date, such as the end of month three, and what happens if the numbers are missed. Why "followers up, sales flat" is the most common agency failure explains which reports to ask for.
A short example brief
This is how it might read for a small firm.
"We are a six-person accountancy firm in Northampton serving owner-managed businesses with turnover under £2 million. We want eight enquiries a month from owners in the area, each worth about £1,800 in first-year fees. Our audience is owners and finance managers who ask us about VAT, payroll and year-end. We want more recurring work and less one-off tax advice. We will not mention competitors, promise tax savings or comment on political matters. One partner approves posts within two working days. The agency will have a 30-minute call with a partner each month. Budget is £900 a month plus any ad spend. We review at the end of month three against enquiries and cost per enquiry."
That is 120 words, and it gives an agency far more to work with than most briefs.
Who should write the brief
The person who owns the result should write it, even if the agency tidies it afterwards. That is usually the owner, a managing partner or a marketing lead.
Set aside an hour with the notes in front of you: your last ten enquiries, your best customer, your worst enquiry and the three questions you hear most. The brief writes itself from those.
Do not ask the agency to write the brief for you. It will describe your business in its own terms, and you will approve it because it sounds reasonable.
Questions a good agency asks back
Expect questions. An agency that has read the brief might ask which customers you want more of, what happened with earlier marketing, how fast you can reply to an enquiry, and who owns the social accounts.
The last one matters. You should own the login details and the page, and the agency should be an admin. If the agency owns them, leaving later is hard. Our guide on what happens when you leave an agency covers this.
An agency that asks nothing and starts posting in a week has not read the brief.
When to update the brief
Review the brief every quarter and after any big change, such as a new service, a price change, a new competitor or a rule change in your sector.
Keep it short enough that people read it. If the brief grows to ten pages, nobody follows it, and the agency will fall back on the calendar.
What a good agency does with the brief
A good agency reads the brief and asks questions. It will say which parts are unclear, which goals look unrealistic and what it needs from you.
It will also propose a sample month before you commit. Ask for that, and judge it against your do-not-say list and your audience's questions. Our guide to what a marketing proposal should contain sets out what to expect, and the questions to ask a marketing agency helps with the conversation.
An agency that accepts any brief without comment is probably not reading it.
Next steps
Growthcart is a digital marketing agency in Northampton. If you would like a second pair of eyes on your brief, or want us to help write it, get in touch.
