One-install Mailchimp Marketing API 3.0 suite admitting all 294 operations in the current official 3.0.91 contract across this backward-compatible 71-operation core and four bounded dependency packs. The default egress base is https://us1.api.mailchimp.com/3.0; enroll a Mailchimp connection named mailchimp with HTTP Basic auth using any non-empty username and the API key as the password, and set base_url to the account data-center host when it is not us1. Coverage includes audiences and contacts, classic lists and members, campaigns and reports, email and SMS send controls, automations and customer journeys, templates and files, landing pages, connected sites, conversations, exports, JSON batch jobs and batch webhooks, verified domains, and complete ecommerce administration. Reads are grant-controlled and approval-free. Writes are grant-off and approval-gated; destructive and administrative operations require approval every run. The original 71 operation IDs and three v2 workflows remain stable for compatibility.