Send a letter from Kiro.

Add paperplane to Kiro’s mcp.json and it can quote and send a real USPS letter — no account required, free sandbox mode included.

Free to preview — see the exact PDF before you pay. Sending starts at $1.99, no account required.

Set it up in Kiro

Step 1

Add to .kiro/settings/mcp.json

Kiro has open bug reports on streamable-HTTP detection (sometimes misread as SSE) — a known rough edge.

{
  "mcpServers": {
    "paperplane": {
      "type": "streamableHttp",
      "url": "https://sendpaperplane.com/api/mcp"
    }
  }
}

Try it: free, nothing mailed

Tell your agent:

Using the paperplane tools, quote a 1-page certified letter to Property LLC, 1 Main St, Richmond VA 23220, then send it in sandbox mode.

Not on Kiro? Any surface works.

The same three calls from the CLI, any MCP client or plain REST. Sandbox is free and mails nothing.

Send a letter

{
  "mcpServers": {
    "paperplane": {
      "type": "streamableHttp",
      "url": "https://sendpaperplane.com/api/mcp"
    }
  }
}

All agents · API docs

Common questions

The connection isn’t working — what should I check first?

Kiro has open bug reports around streamable-HTTP detection, sometimes misread as SSE. That’s a known rough edge to check for before assuming the config above is wrong.

What tools does Kiro get?

quote_letter, send_letter, and get_letter_status for mailing, plus buy_credits for pre-funding sends. Postcards are live (from $1.99) via the REST API’s format field, though not yet an MCP tool argument.

How much does sending cost?

Letters start at $1.99 for First-Class; Certified Mail starts at $12.99. Every quote shows the exact total before you approve anything, and sandbox mode is free.