One-install Mercury API capability pack over accounts, balances, transactions, statements and PDF capture, credit and Treasury, cards, recipients and approval requests, accounts receivable, categories, events, users, SAFEs, and Mercury Books. Read groups install by default; every mutation needs an explicit capability grant, all mutations still ask for approval, and money movement, payment requests, deletions, and cancellations require approval every run. The pack uses Mercury's bearer-token flow, supports cursor, offset, and page-token pagination, and bundles seven operating briefs plus four guarded intakes/actions. It intentionally excludes multipart attachment upload, partner onboarding, and webhook endpoints whose documented responses expose signing secrets; it never accepts credentials or arbitrary paths as arguments.