Begin with the problem you are solving, not a list of screens. What kind of user will use this, how often, and how is the job done today? A vendor who grasps the purpose can propose a simpler way to reach it; a team that receives only a feature list can only price your assumptions along with the work.

Define what is included as short scenarios: what the user does and what the system does in response. Every bit as useful, state explicitly what is out of scope. A written out-of-scope list removes more friction at delivery time than almost anything else in the document. Also mark which parts are firm and which are still open — the difference changes the price, and pretending everything is fixed helps no one.

Set out your constraints. This means existing systems the software has to talk to, laravel vs nextjs the data you have and where it lives, regulatory obligations, expected load, target platforms and infrastructure that is already decided. Where a date is genuinely fixed, explain what drives it: a good team is usually able to rearrange the plan to meet it, but only if they know it exists.

Define what the word done means feature by feature. Clear acceptance criteria do not need any formal notation: a short paragraph setting out what a user should be able to do is sufficient. This single habit compresses acceptance testing by a surprising margin and closes off most late-stage disagreement.

One last thing, ask for a specific format. Require an itemised estimate, the assumptions behind each number, the main risks and an optimistic and a pessimistic figure. Read a wide range as useful information rather than evasion: it tells you exactly which requirement is unclear. At that point tighten that section and monolith vs microservices comparison ask for a new estimate — the second estimate is the one worth planning around.