UX deliverables for UI/visual design outsourcing

I have been working on a mobile application design: conducted the user research, designed and iterated the wireframes, and did a clickable prototype of the app. Now we need to do the UI + visual design of the application, and we're outsourcing it to external agency (the development is done by other vendor). I wonder what should I deliver to them 1) For them to understand the scope of work and give me a timeframe estimate 2) The full package needed for them to do their job.

I think that the app description + wireframes + interactive prototypes + scope of work (what exactly needs to be delivered) are enough to understand the amount of work, while for the total work I can supply them with personas, user stories and use cases (user journey not relevant in this case. Is there anything else that may be needed for the two phases?