Open with the problem you are solving, not a list of screens. Who will use it day to day, how many times a day, and what does the process look like without it? A vendor who grasps the purpose often proposes an alternative that costs less; one who only sees the requirements as given prices your assumptions along with the work.
Describe the scope as user stories or scenarios: get a software development quote walk through each important path. Every bit as useful, list what you are not building. An explicit exclusion list prevents more disagreement later than any other single page. Also mark which items are decided and which are still under discussion — honest teams price those differently, and hiding it helps no one.
Set out your constraints. The list covers systems you must integrate with, existing databases and their quality, compliance requirements, aws development agency expected load, target platforms and any technology you are committed to. If a deadline is real, explain what drives it: a team is usually able to resequence the work to meet it, provided they hear about it early.
Say what the word done means for each item. Acceptance criteria do not need formal language: a plain-language note describing what must be true when the feature works is enough. This single habit shortens the sign-off process dramatically and eliminates the most common source of disputes.
To close, state what you want in the response. Require a task-level breakdown, the assumptions behind each number, the risks the team sees and a range rather than a single figure. Read a wide range as a signal about the brief: it normally identifies where your description is thin. At that point tighten that section and request a revised number — the next version is the one worth planning around.