A number produced without questions counts as a red flag rather than good service. A competent team responds with questions first: about integrations. A provider that quotes without asking anything is simply guessing, and the gap will be corrected later — and you will pay for it.
Be wary of a mismatch between the engineers on the sales call and the developers actually assigned. Insist on the names and CVs of the actual team in the agreement, livewire or vue with a provision about substitutions. A vendor edtech software development that only offers a pool of resources and will not commit to individuals is keeping its own flexibility at your cost.
Require commit-level visibility from the first week. A partner that hands over a build only at the end of each phase is asking you to take delivery on faith. Daily commits show you who is really on the project far better than a slide deck. The same applies to the CI pipeline: if nothing runs automatically, hire node js developers promises about quality are just talk.
Ambiguous wording in the contract around intellectual property is never a formality. The contract should state in plain terms that all outputs produced under it transfer to the client as they are paid for. Check also the jurisdiction and the milestone terms: heavy prepayment with nothing due in return for weeks takes away your only leverage.
Lastly, examine communication. Ask what overlap the teams will share each day, which named person is expected to answer day-to-day questions and within what time. A few hours of overlap is usually enough; none at all turns a five-minute question into a lost day. Careless writing in the early emails will not improve once the work starts.