Open with the reason this enterprise software development with java should exist, not your preferred technology. Which people will use the system, with what frequency, symfony enterprise applications and what happens today? A vendor who understands the goal often proposes an alternative that costs less; one who only sees a feature list can only price your assumptions along with the work.
Describe the scope as short scenarios: a walk through each important path. Just as important, state explicitly what you are not building. A written out-of-scope list saves more friction later than almost anything else in the document. Mark too which parts are firm and vue js vs angularjs which are still open — the difference changes the price, and pretending everything is fixed helps no one.
Set out your constraints. These include the platforms and services involved, existing databases and their quality, regulatory obligations, traffic expectations, target platforms and infrastructure that is already decided. If there is a hard date, say why: an experienced team is usually able to rearrange the plan to meet it, provided they hear about it early.
Define what completion means for each item. Clear acceptance criteria do not need any formal notation: a short list setting out what a user should be able to do is enough. This one section shortens the review at the end considerably and eliminates the usual argument at handover.
One last thing, say what you expect back. Ask for a task-level breakdown, a written list of assumptions, the risks the team sees and an optimistic and a pessimistic figure. Take a broad range as a signal about the brief: it usually points to the part of the brief that needs work. At that point tighten that section and ask again — the next version is far closer to reality.