A named decision-maker, access to the code and design material that exists, and a realistic view of the deadline. Everything else can be worked out between us.
The most common difficulty in an engagement is not technical; it is a team that cannot make a decision in the time the sprint needs, and the fix for that is agreeing up front who decides. If a milestone review lands and nobody in the room can approve a course change, the sprint stalls — the code is fine, the calendar is not. Naming the person now costs a sentence in the kickoff notes and saves weeks later.
We also want to hear where you think the risk sits, in your own words. A team that has already decided which part of the build worries them most is a team we can help quickly, because we spend less of the discovery pass finding the problem and more of it on the fix.