You do not need a finished brief before speaking with a developer. You do need a clear sense of what feels difficult today and what you hope will be easier after the project.
Bring the context
Share your audience, offer, current website, important examples, content you already own, integrations, decision-makers, timing, and constraints. Bring the questions customers ask and the parts of the current workflow that create friction.
Bring uncertainty too
It is useful to say what you do not know. A good discovery conversation should turn uncertainty into decisions, options, or a small piece of research—not pretend every answer is obvious.
Start a website conversation with the problem in your own words.