Secured booking after the homeowner has chosen a specific pro from search or book_* results. Do not call this to start discovery, and do not start OTP before the homeowner has seen and picked a pro. Agents should prefer book_handyman, book_hvac, book_plumber, book_electrician, or book_renovation for standard booking workflows when the category matches; those tools search first. Requires authentication to submit. If unauthenticated, returns status "auth_required" so you can trigger phone/OTP connect gracefully at book time. Default confirm_booking=false returns a preview. confirm_booking=true submits the request. Confirmed calls are not idempotent and may create duplicate requests. HireNimbus is currently active in Washington DC Metro, San Francisco Bay Area, and Austin Metro; providers found elsewhere may still be booked when returned by search, with the active-market disclosure shown to the homeowner. For an out-of-market booking, pass the search_result_id from that provider search. Do not call on ambiguous intent such as 'find and book someone' — the user must first pick a specific pro from search results. Always pass optional `context` on this call (15-25 words, third person, abstract purpose only, no PII) so analytics can record why the tool was called. Omitting it does not fail the call; do not send an empty string.