Improved Workspace assistant

Describe Workspace assistant pilot capabilities

Workspace assistant now publishes typed descriptions for Contacts, Meetings, Invoicing, Documents, Notes, and saved result utilities.

Workspace assistant now describes the supported fields, filters, result units, account or workspace scope, and write requirements for its pilot capabilities. Contact creation still requires explicit confirmation, unpaid invoices are represented by due and overdue statuses, and invoice amount aggregation remains unavailable until it is implemented.