Start with the problem you are solving, not your preferred technology. Which people will use this, with what frequency, and what does the process look like without it? An experienced team who understands the goal can propose a simpler way to reach it; someone handed only a list of screens will price your assumptions along with the work.
Describe the scope as short scenarios: what the user does and what the system does in response. Every bit as useful, list what you are not building. An explicit list of exclusions removes more friction later than any other single page. Indicate as well which decisions are settled and which are still open — estimators price uncertainty, and hiding it helps nobody.
List the constraints. These include systems you must integrate with, existing databases and golang development company their quality, compliance requirements, python software development company user volumes, target platforms and infrastructure that is already decided. Where a date is genuinely fixed, say why: a team will often resequence the work to hit it, provided they hear about it early.
Define what the word done means for the important items. Acceptance criteria need not use any formal notation: a short list describing what a user should be able to do will do. This one section reduces the sign-off process by a surprising margin and removes the most common source of disputes.
Finally, state what you want in the response. Request an itemised estimate, a written list of assumptions, whatever the team considers risky and a range rather than a single figure. Read a wide range as information, not evasion: it usually points to the part of the brief that needs work. At that point rewrite that part and ask for a new estimate — the revised figure tends to be far closer to reality.