An estimate that arrives instantly is a red flag rather than good service. A competent team will come back with a list of questions: about users and volumes. A vendor that prices with no clarification is probably pricing a guess, custom software development vs saas and a guess becomes a change request later — at your expense.
Be wary of any distance between the team in the pitch and the developers actually assigned. Ask for the names and CVs of the actual team in the agreement, with a provision that requires notice before anyone is swapped. A vendor that talks only about roles and refuses to name people is keeping the right to assign anyone it likes.
Require the source repository from the start. A partner that delivers code only at milestones is inviting you to accept a black box. Visible commits tell you the actual pace far better than a weekly report. The same applies to the automated test suite: if nothing runs automatically, promises about quality are nothing more than words.
Ambiguous wording in the contract around IP is never a formality. The agreement must state in plain terms that all outputs produced under it transfer to the client on payment. Also check which country’s law applies and the milestone terms: a large upfront payment with nothing due in return for weeks removes the only leverage you have.
Finally, pay attention to communication. Confirm what overlap the teams will share with your working day, who handles your questions and ai development company within what time. A few hours of overlap is normally sufficient; no overlap stretches a five-minute question into a lost day. Careless writing in the early emails does not improve once the work starts.