Begin with the problem you are solving, not your preferred technology. Who will use it day to day, with what frequency, and how is the job done today? An estimator who knows what you are trying to achieve will suggest an alternative that costs less; one who only sees a feature list can only price the list as written.
Define what is included as short scenarios: what the user does and what the system does in response. Equally important, write down what is out of scope. A written out-of-scope list saves more argument later than the rest of the brief combined. Mark too which parts are firm and which are still under discussion — the difference changes the price, and aws software development company hiding it helps no one.
Write down the hard constraints. The list covers the platforms and mvp development services involved, existing databases and their quality, security and compliance rules, user volumes, supported browsers or devices and any technology you are committed to. If there is a hard date, say why: a team is usually able to cut the right scope to meet it, but not if the date is a secret.
Say what completion means for the important items. Testable acceptance criteria do not need any formal notation: articles on software outsourcing a short paragraph setting out what must be true when the feature works will do. This single habit compresses the review at the end considerably and closes off most late-stage disagreement.
One last thing, ask for a specific format. Ask for an itemised estimate, a written list of assumptions, whatever the team considers risky and a low number and vue js web app development a high number. Take a broad range as a signal about the brief: it usually points to the part of the brief that needs work. From there rewrite that part and request a revised number — the revised figure is far closer to reality.