All five tools have clearly distinct responsibilities: invoice lookup/creation are separate, and net-worth/source actions are separate. get_source and list_sources follow the standard item-vs-collection pattern. There is no meaningful overlap.

Names consistently follow a verb_noun pattern: get_invoice, create_invoice, list_sources, get_source, and get_net_worth. The convention is uniform and predictable across both subdomains.

Five tools is a compact, appropriate size for a server covering Checkout invoices and Watchlist reads. Each tool serves a distinct need without redundancy.

The invoice side covers create and lookup but not list, cancel, or update operations, and the Watchlist side is read-only with no way to add or edit sources. These are notable lifecycle gaps, though the core read and checkout workflows are present.