> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sendmypaper.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Send a postcard

> Ask your agent for a 4×6 or 6×9 postcard with a photo or big headline on the front.

## What to tell your agent

Give it four things, or let it ask:

1. **Who it's to**: name and full US address.
2. **The front**: a photo (an https link, or one you've shared) or a few words of big text.
3. **The message** for the back, up to 600 characters. Your agent can draft it.
4. **Your return address**: it's printed on the card.

> Send a 6×9 postcard to Sam Rivera, 12 Oak St, Austin TX 78701, with this photo on the front. On the back: "Thirty looks great on you. Dinner's on me." From Alex Kim, 88 Pine Ave, Denver CO 80202.

## What happens

* The agent calls `create_postcard` with `size` `4x6` or `6x9`.
* It shows you the **preview**: the front, and the back with your message and addresses.
* It pays with your approval ([agent payments](/guides/agent-payments)) or gives you a checkout link.

## Design tips

* **Photos:** landscape works best. Aim for at least 1800 × 1200 px for 4×6 and 2700 × 1800 px for 6×9. They're cropped to fill the card.
* **Text-only fronts:** keep `front_headline` short (it fits about 60 characters) and pick a `front_theme`: `ink`, `sky`, `sunset` or `forest`.
* **Messages:** short is better. 600 characters fills the space comfortably.


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.