# eSIM Tabby

> Prepaid travel eSIM data plans, sold through a Model Context Protocol server that an AI assistant calls directly. Search the catalogue by country and data allowance, buy, and get back the activation QR code — all inside the conversation.

Connect a client to https://esimtabby.com/mcp (streamable HTTP). The first call runs an OAuth sign-in. Payment is a hosted Stripe checkout link a human opens in a browser, or USDC over x402 for an agent that holds a wallet — no browser step. We never see card details.

## Server

- [MCP endpoint](https://esimtabby.com/mcp): tools to search plans, check coverage, buy, top up, and read back activation details and data usage.
- [Server card](https://esimtabby.com/.well-known/mcp/server-card.json): transport, auth and payment metadata as JSON.
- [For agents](https://esimtabby.com/agents): connect instructions for Claude, Cursor, ChatGPT and any other MCP client, with the payment rails compared.
- [Plan catalog](https://esimtabby.com/catalog.md): live prices for the top destinations, as a markdown table.

## Guides

- [Building an MCP server that takes money](https://esimtabby.com/guides/mcp-server-that-takes-money): An MCP tool must never charge a card or accept a price as an argument. How eSIM Tabby authenticates, prices and settles agent purchases, with the code.
- [What happens when an AI agent buys an eSIM with USDC](https://esimtabby.com/guides/x402-in-production): An AI agent orders a travel eSIM, gets an HTTP 402 quoting USDC on Base, signs an EIP-3009 authorisation, and the eSIM is issued. The x402 flow in production.
- [eSIM not working? Find your symptom, then the fix](https://esimtabby.com/guides/esim-not-working): Nine times out of ten it is data roaming switched off on the travel line. Find your exact symptom — no service, no data, failed QR — and the fix for it.
- [How to activate an eSIM on iPhone without a surprise bill](https://esimtabby.com/guides/activate-esim-iphone-without-surprise-bill): Your travel eSIM needs data roaming on and your home line needs it off. Two same-looking toggles one menu apart, and the four-minute check that keeps a $9 trip from becoming a $300 one.

## Legal

- [Terms](https://esimtabby.com/legal/terms)
- [Privacy](https://esimtabby.com/legal/privacy)
- [Refunds](https://esimtabby.com/legal/refunds)
- [Contact](https://esimtabby.com/legal/contact)