[CONFIRM: What permission level is appropriate?]
For the full breakdown of each Box collaborator role (Co-owner, Editor, Viewer Uploader, Previewer Uploader, Viewer, Previewer, Uploader) and the exact capabilities each grants, see the role matrix in the box skill's references/collaboration.md. Use that matrix to determine which role fits a given collaborator, then have the human confirm the choice before granting access.
Apply least privilege: default to the most restrictive role that still lets the collaborator do their job, prefer specific folders over root access, and set expiration dates on external collaborations.