Start with the problem you are solving, not a feature list. 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 a cheaper route to it; one who only sees the requirements as given can only price the list as written.
Describe the scope as user stories or scenarios: a walk through each important path. Equally important, state explicitly what you are not building. An explicit exclusion list saves more argument during acceptance than almost anything else in the document. Mark too which parts are firm and which are still open — the difference changes the price, and concealing the open questions helps no one.
Set out your constraints. The list covers the platforms and java consulting services involved, the data you already hold and software livewire its condition, regulatory obligations, traffic expectations, supported browsers or devices and infrastructure that is already decided. If a deadline is real, say why: an experienced team is usually able to rearrange the plan to meet it, but not if the date is a secret.
Write down what done means for the important items. Testable acceptance criteria need not use formal language: kubernetes web development company a plain-language note setting out what must be true when the feature works is enough. This one section compresses the review at the end by a surprising margin and removes most late-stage disagreement.
One last thing, ask for a specific format. Require a task-level breakdown, the assumptions used, the risks the team sees and an optimistic and a pessimistic figure. Read a wide range as information, not evasion: it usually points to exactly which requirement is unclear. Then tighten that section and ask again — the next version tends to be far closer to reality.