Begin with the business problem, not a list of screens. Which people will use this, how often, and how is the job done today? An estimator who understands the goal will suggest a cheaper route to it; someone handed only a list of screens will price your assumptions along with the work.
Set out the scope as concrete flows: who does what, and what happens next. Just as important, write down what the first release deliberately excludes. An explicit list of exclusions prevents more friction later than the rest of the brief combined. Mark too which items are decided and swift app development company which may still change — estimators price uncertainty, and pretending everything is fixed helps nobody.
List the constraints. These include the platforms and services involved, existing databases and their quality, security and compliance rules, traffic expectations, which devices matter and infrastructure that is already decided. If a deadline is real, explain what drives it: a good team will often rearrange the plan to meet it, provided they hear about it early.
Write down what the word done means feature by feature. Testable acceptance criteria need not use formal language: a short list setting out what a user should be able to do will do. That one addition reduces acceptance testing by a surprising margin and eliminates most late-stage disagreement.
To close, state what you want in the response. Request a breakdown by feature or module, the assumptions behind each number, the main risks and a low number and a high number. Take a broad range as information, react js development agency not evasion: it usually points to where your description is thin. Then tighten that section and ask for a new estimate — the next version is much more reliable.