A dedicated AP automation tool typically captures incoming vendor bills (from email, a vendor portal, or a scanned document), extracts the relevant data, routes it for approval based on configurable rules, and then pushes the finished bill into Sage Intacct as a payable transaction. This covers the common case well: a standard vendor bill, a standard approval chain, posted to a standard set of accounts.
Where it gets more involved is dimension tagging. Sage Intacct's whole value is multi-entity, multi-department reporting, which means every AP transaction needs the right entity, department, and class tags to actually be useful in your reporting later. A generic AP tool's default mapping handles simple cases but often needs real configuration, or custom logic layered on top, to tag bills correctly when your approval and coding rules are more specific than "one vendor, one account."
On the accounts receivable side, Intacct handles standard invoicing and billing schedules well on its own, with the complexity usually showing up around recurring billing and revenue recognition timing rather than the invoice creation itself.