Start with the reason this custom real estate software development should exist, not your preferred technology. Who will use this, how many times a day, and how is the job done today? A vendor who knows what you are trying to achieve often proposes a cheaper route to it; someone handed only a list of screens can only price your assumptions along with the work.
Set out the scope as user stories or scenarios: who does what, and what happens next. Equally important, write down what the first release deliberately excludes. A written out-of-scope list saves more argument at delivery time than almost anything else in the document. Mark too which parts are firm and which may still change — the difference changes the price, javascript seo agency and pretending everything is fixed helps no one.
Set out your constraints. The list covers the platforms and services involved, the data you already hold and its condition, regulatory obligations, expected load, which devices matter and any technology you are committed to. If there is a hard date, explain what drives it: a good team can often resequence the work to hit it, provided they hear about it early.
Define what completion means for each item. Testable acceptance criteria do not require any formal notation: a plain-language note describing the expected behaviour is sufficient. This one section reduces the review at the end dramatically and outsource aws development eliminates the most common source of disputes.
To close, ask for a specific format. Require an itemised estimate, python v php 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 normally identifies the part of the brief that needs work. From there rewrite that part and request a revised number — the revised figure is the one worth planning around.