Open with the problem you are solving, not a feature list. Who will use this, with what frequency, and what does the process look like without it? A vendor who knows what you are trying to achieve will suggest a simpler way to reach it; a team that receives only a list of screens prices exactly what you asked for.

Set out the scope as short scenarios: a walk through each important path. Every bit as useful, write down what the first release deliberately excludes. An explicit exclusion list saves more friction at delivery time than almost anything else in the document. Indicate as well which decisions are settled and which may still change — the difference changes the price, outsource mobile app development and hiding it helps no one.

Set out your constraints. The list covers the platforms and services involved, existing databases and their quality, compliance requirements, user volumes, target platforms and any technology you are committed to. If a deadline is real, say why: a good team is usually able to cut the right scope to protect it, but only if they know it exists.

Say what completion means for the important items. Clear acceptance criteria do not need any formal notation: a short list setting out what a user should be able to do is sufficient. This single habit shortens the review at the end by a surprising margin and closes off the usual argument at handover.

Finally, say what you expect back. Require a breakdown by feature or module, the assumptions used, hire laravel framework developers whatever the team considers risky and a low number and a high number. Take a broad range as a signal about the brief: it usually points to where your description is thin. Then rewrite that part and request a revised number — the second estimate tends to be the one worth planning around.