Begin with the reason this software should exist, not a list of screens. Who will use this, hire flutter developer with what frequency, and what happens today? An estimator who knows what you are trying to achieve can propose a cheaper route to it; someone handed only a feature list can only price your assumptions along with the work.
Set out the scope as user stories laravel or symfony scenarios: who does what, and what happens next. Every bit as useful, state explicitly what is out of scope. A written out-of-scope list saves more friction at delivery time than the rest of the brief combined. Indicate as well which items are decided and which are still open — honest teams price those differently, and hiding it only hurts you.
Set out your constraints. The list covers the platforms and services involved, the data you already hold and its condition, security and compliance rules, software development company in uae traffic expectations, target platforms and infrastructure that is already decided. If there is a hard date, say why: custom typescript app development a good team can often cut the right scope to hit it, but only if they know it exists.
Define what the word done means feature by feature. Testable acceptance criteria need not use any formal notation: a plain-language note stating what must be true when the feature works is sufficient. That one addition shortens acceptance testing dramatically and closes off most late-stage disagreement.
One last thing, ask for a specific format. Ask for a task-level breakdown, the assumptions behind each number, the main risks and a low number and a high number. Read a wide range as useful information rather than evasion: it normally identifies the part of the brief that needs work. Then tighten that section and ask for a new estimate — the second estimate tends to be the one worth planning around.