Faxer — Send Faxes vs Echo MCP

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get_fax_quote

Get the exact price to send a real fax to any US, Canadian, or international fax number via faxer.me. Call this first whenever a user wants to send, transmit, or fax a document or message. Provide document_url (a publicly downloadable PDF), cover_text (plain text that will be rendered onto fax pages), or pages (an estimated page count). Pricing is pay-per-fax ($1.00 first page + $0.25/page, returned in USD cents); no account or API key needed.

create_fax_payment

Create a Stripe Checkout payment link for a fax. Returns payment_url — give this link to the human so they can pay in their browser (agents never handle card details) — and payment_id, which you pass to send_fax after the human has paid. The price is computed server-side from the document or text. The Checkout link expires (see expires_at, ~24h); create a fresh one if the human delays.

send_fax

Transmit a fax. Two ways to pay: (1) human-in-the-loop — pass the payment_id from create_fax_payment after the human has paid the Stripe Checkout link; (2) autonomous machine payment (x402/MPP) — call WITHOUT payment_id and the server replies with a payment challenge (JSON-RPC error -32042) for USDC-on-Tempo or a Stripe Shared Payment Token; pay it and retry with the credential in _meta['org.paymentauth/credential']. Either way the server verifies the payment covers the server-computed price of the actual content before sending via a real fax carrier. One fax per payment; card/Checkout and Stripe machine payments are refunded automatically if the fax fails to send or deliver (on-chain payments are refunded manually).