Open with the problem you are solving, not a list of screens. Who will use the system, hire ai developers how many times a day, and how is the job done today? An estimator public sector web development who understands the goal will suggest a simpler way to reach it; one who only sees a feature list will price exactly what you asked for.

Set out the scope as user stories or scenarios: who does what, and what happens next. Just as important, write down what you are not building. An explicit exclusion list prevents more friction at delivery time than almost anything else in the document. Mark too which decisions are settled and which are still open — the difference changes the price, and hiding it helps nobody.

Write down the hard constraints. This means the platforms and services involved, existing databases and their quality, compliance requirements, user volumes, which devices matter and any technology you are committed to. If there is a hard date, say why: a good team will often resequence the work to protect it, provided they hear about it early.

Write down what completion means for each item. Acceptance criteria need not use any formal notation: a short list setting out what must be true when the feature works is sufficient. That one addition compresses the review at the end by a surprising margin and removes the usual argument at handover.

One last thing, ask for a specific format. Request a breakdown by feature or module, the assumptions used, the main risks and a low number and a high number. Take a broad range as information, not evasion: it usually points to exactly which requirement is unclear. Then clarify that area and ask for a new estimate — the revised figure is the one worth planning around.