Off-the-shelf tools fit when the workflow itself is generic. Meeting transcription, note capture, document summarization, and standard CRM hygiene look nearly identical from one firm to the next, and vendors have refined those products across hundreds of customers. Buying one is faster and cheaper than building it, and the switching cost if it disappoints is low.
The case for custom agents begins where the workflow carries the firm's own operating judgment: how accounts are opened, which exceptions matter in reconciliation, what a compliance review must evidence, how a reporting package is assembled and approved. A generic tool either cannot see those rules or forces the firm to flatten them into whatever the product supports. Custom agents are built against the firm's actual systems, data, and approval structure — which is precisely what makes the workflow worth automating in the first place.
Either way, a regulated firm should demand the same three things before any automation touches client data: a clear data boundary — knowing exactly where information travels and who can read it, up to and including local LLM deployment inside your compliance boundary when nothing may leave the firm's infrastructure; auditability, meaning a durable record of what was read, produced, and approved; and approval gates, so no automated step reaches a client or a system of record without a named person signing off. A vendor or a builder who cannot answer for all three is not ready for this industry.