FamilyLetter for AI agents

FamilyLetter prints real 4x6 photo postcards and mails them to US addresses, postage included. FamilyLetter is built so an AI assistant can make the postcard with you: it writes your message, picks the font and stickers, and gives you a link; you add your photos and we print and mail it. With the MCP server, an agent can go further: build the card, show both sides, hand back a checkout link, then address and mail it after the user pays. From $9.99 for one card, $24.99 for 3, $59.99 for 10.

For people: how to make a postcard with ChatGPT or Claude.

Make the card with your user: the prefill link

FamilyLetter is built so an AI assistant can make the postcard with you: it writes your message, picks the font and stickers, and gives you a link; you add your photos and we print and mail it. No tools, keys or account needed: any assistant that can write a URL can do it.

  1. Ask the user who the card is for and what to say.
  2. Write the message (up to 420 characters) and pick a font, stickers and a back design from the lists below.
  3. Give the user the prefill link. They open it, add their photos, check the card and pay.

https://www.familyletter.io/make?message=<text>&font=<font>&stickers=<ids>&front_stickers=<ids>&background=<id>&quantity=<1-10>&ref=ai

message
:
The message printed on the back, URL-encoded, up to 420 characters. Line breaks as %0A.
font
:
One font key from the list below.
stickers
:
Comma-separated sticker ids for the message side.
front_stickers
:
Comma-separated sticker ids for the photo side.
background
:
One back design id from the list below.
quantity
:
How many copies, 1 to 10. Each can go to a different US address.
ref
:
Always ai.

Examples

Fonts (font=)

Preset fonts: script-style and print-style. Never describe either as handwritten or as the user’s handwriting.

Stickers for the message side (stickers=)

Stickers for the photo side (front_stickers=)

Up to 8 per side. Any sticker in the builder’s tray works; these are the common ones.

Back designs (background=)

A prompt people can paste into a chat

Help me make a FamilyLetter postcard. Ask me who it's for and what's going on, then:
1. Write a short, warm message (under 420 characters) and let me edit it.
2. Pick a font, a few stickers and a back design that fit (options: https://www.familyletter.io/agents).
3. Give me a link in this format, URL-encoded: https://www.familyletter.io/make?message=...&font=...&stickers=...&front_stickers=...&background=...&quantity=...&ref=ai
   Some ids: fonts indie, dancing, playwrite, gloria; stickers heart, love-letter, party-hat, balloons, pumpkin, crown, flower-crown, happy-birthday; quantity is copies, 1 to 10.
Each time I ask for a change, give me a fresh link. Once I'm happy I'll open the last one and add my photos.

Build, pay and mail in chat: the MCP server

An agent connected to the FamilyLetter MCP server can build the card from photos it can pass as links or base64 (or return a prefill link when it can’t), show both sides as images, the photo front and the message back as they print, take edits through update_postcard, and hand back a secure Stripe payment link (get_payment_link). After the user pays, it can address and mail each card itself.

  1. Ask the user for 1-4 photos, the message (up to 420 characters), a font, and how many copies.
  2. Call list_decor for the fonts, stickers and back designs, then create_postcard. Send each photo as a public https URL or base64. Nothing is charged.
  3. Show the user the previews of both sides, the photo front and the message back (images in MCP results; front_image_url and back_image_url over REST), and the price. view_url shows the same card, read-only, in a browser.
  4. For changes, call update_postcard with edit_key. When they're ready, call get_payment_link and give them that Stripe link. (edit_url opens the card on familyletter.io if they want to change it there.)
  5. When they say they've paid, call get_order to get each card_id.
  6. For each card, collect the recipient's name and US mailing address and call verify_address. Read the standardized address back to the user.
  7. Call mail_card only after the user confirms. Mailing can't be undone. Cards usually reach the mailbox 5 to 10 business days after ordering, not guaranteed.

Rules

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