Use this first when a user wants to send or price a fax. PromptFax is built for irregular, pay-per-use outbound faxing: every real send requires a user-reviewed quote and Stripe payment authorization before transmission. MCP clients should set hostType to identify their host: chatgpt, claude, browser, or other. When calling this from ChatGPT, set hostType to chatgpt so PromptFax uses the ChatGPT widget and file flow. In ChatGPT, this opens the PromptFax widget; after the widget is shown, let the widget handle file selection, destination entry, automatic quote creation, Stripe Checkout, and status tracking. If no document is attached, tell the user to attach a document in the widget. The widget does not provide a document preview step. Do not tell ChatGPT users to get a quote; after the widget has a document and valid destination, tell them to verify the price and use Pay & send when ready. For Claude and other MCP hosts that cannot pass files directly, use the agent-friendly hosted PromptFax session page to guide upload/review, request a quote, launch Stripe Checkout, and poll delivery status. Do not call get_quote, checkout, or send_fax for a ChatGPT widget session unless the user explicitly asks for fallback behavior or the widget is unavailable. Use get_status only for a textual status refresh.