As with all writing it is important to remember your target audience. Web designers & developers are generally pretty intelligent people (honest!) but they will not necessarily have an understanding of your particular industry. So while there is no need to spell out every single detail you should not assume they will be familiar with any industry specific terminology or work practices. With that in mind let's break down what an ideal brief would consist of...
This would be a short section, maybe just one paragraph, which would present the main aims of the project - is it an ecommerce store selling socks? A membership portal with paid & free registration options? A dating app with a twist? Include whatever makes this project unique and what it is intended to achieve, but don't get bogged down in detail. This section is often used as a basis for setting up 'success metrics' to track how successful the final project is in achieving it's goals.
Often clients will have their own thoughts on design, there may already be a logo or colour scheme to work to. This is absolutely fine - provided we know from the start. There is nothing more annoying than spending 4 weeks on an exciting new design, only to be told 'oh actually I quite like the way Amazon looks, can you make it like that please?'. Designers are sensitive souls, every discarded design leaves a fresh scar that only time and copious amounts of praise can ever truly erase.
Producing a full brief requires the client to think through every aspect of their project. So taking a membership portal as an example you would need to consider:
Do you need different levels of membership?
If so how do these levels differ - what do they offer?
What payment methods will you accept?
What information do you need to collect on registration?
Is it an annual membership fee or one off?
It is generally a good idea to define which features are a 'must have' and which are a 'nice to have' so that any budget or time constraints can be worked around. For large, custom projects with very specific requirements this can be quite a long section.
Budget and Timescales
Web design agencies tend to be very busy (at least the good ones are!) and can get booked up weeks or months ahead so it is important to define a realistic target date for your project to launch. Likewise a realistic budget is a must, asking an agency to build a completely bespoke website and app within 2 weeks for £1,000 will not be met with a hugely positive response.
Any Other Information
Is your project dependant on government funding? Is it highly time sensitive? Do you need a full launch campaign planned? Does it need translating into 16 languages including Eskimo? The more information you can give at this stage the easier it is for your chosen design agency to provide an accurate quote and ultimately deliver the website you need.
What you don't need to do
As the client you would not be expected to have any technical knowledge whatsoever. You do not need to suggest what technology is used, what platforms are preferable or anything like that. Of course if you have knowledge in this area and your own platform preferences by all means share them. If your chosen agency disagrees they will be happy to explain their reasons.
Your web design agency will utilise your brief to create a quote and timescale for your project. They may also write up a technical spec with you which will detail exactly how they will go about creating your project - the coding language, platform etc, restate the required features from your brief and expand on them to ensure they understand every detail of what you are after. This helps avoid any confusion and gives you both a checklist to run through on completion of the project to ensure that everything agreed has been done.
I have genuinely received the following 'briefs' in the past:
While web designers do their very best to accommodate any request, those are beyond even them!