Start with the reason this software should exist, not a list of screens. Which people will use the system, how often, and what happens today? An estimator who understands the goal often proposes a simpler way to reach it; someone handed only a feature list prices exactly what you asked for.
Define what is included as user stories or scenarios: who does what, and what happens next. Equally important, state explicitly what the first release deliberately excludes. A written out-of-scope list removes more disagreement during acceptance than the rest of the brief combined. Indicate as well which parts are firm and which are still under discussion — honest teams price those differently, and hiding it helps nobody.
Set out your constraints. These include existing systems the software has to talk to, python outsourcing company the data you have and where it lives, regulatory obligations, expected load, which devices matter and infrastructure that is already decided. If a deadline is real, .net consulting services say what depends on it: a team can often rearrange the plan to protect it, provided they hear about it early.
Write down what the word done means for each item. Testable acceptance criteria do not require formal language: a plain-language note stating what a user should be able to do will do. That one addition shortens acceptance testing dramatically and removes the usual argument at handover.
Finally, say what you expect back. Ask for an itemised estimate, the assumptions used, whatever the team considers risky and an optimistic and a pessimistic figure. Take a broad range as useful information rather than evasion: it normally identifies the part of the brief that needs work. Then rewrite that part and ask again — the revised figure tends to be the one worth planning around.
