A useful brief starts with the business outcome, the audience and the evidence you need to make decisions.
Define the change you need
More posts is an activity. More qualified enquiries is a business goal. Start by describing the change you want to see, how you currently measure it and what would make the work worthwhile.
Know who the work is for
An agency needs to understand the customer, the buying situation and the objections. Bring real questions from sales conversations, enquiries and support requests rather than relying only on a broad demographic profile.
Make the offer clear
A campaign cannot resolve every weakness in an unclear offer. Explain what is being sold, why it matters and what happens after somebody clicks or sends a message.
Agree the responsibilities
List the inputs you will provide, who can approve the work and which tools or accounts are involved. Clear ownership helps prevent delays and makes feedback more useful.
Decide what evidence matters
Agree what will be measured, where that information comes from and how often it will be reviewed. A useful report explains what happened and what decision follows, while recognising the limits of the data.