List Vercel team members and roles

List a Vercel team's members with their username, email and role. Read-only — changes nothing. Pass the optional email arg to also get a present true/false verdict for that address, which is the quick way to confirm an offboarding landed. team is required (the team's URL slug). Requires being signed into Vercel. Complements vercel.com/delete_user, which already snapshots the member list before and after its own action.