Use paperplane in Grok

Grok supports custom remote MCP servers — both in the grok.com web app (Connectors) and in the xAI API (Remote MCP Tools). paperplane’s MCP server is a public streamable-HTTP endpoint with no API key, so connecting is genuinely just pasting a URL. To be clear about what this is: this is user-side setup. paperplane has no native listing in Grok’s connector directory today — you are pointing Grok at our standard MCP endpoint yourself, the same endpoint Claude, Cursor, and every other MCP client uses.

Connect it (web app)

• Open grok.com/connectors and click New Connector.
• Choose Custom.
• Paste the server URL: https://sendpaperplane.com/api/mcp. No authentication — the server supports anonymous access, so there is no OAuth flow to complete.
• Save. Grok discovers the tools and exposes them in your next chat: quote_letter, send_letter, and get_letter_status.

What the three tools do

• quote_letter — read-only and free. Prices a letter (First-Class $1.99, Certified $12.99, Certified + electronic Return Receipt $14.99, Priority $24.99) with the all-in total, and — when given the real recipient and content — mints a single-use confirmation_token bound to that exact letter.
• send_letter — the one write tool: it spends money and mails a physical object. It refuses to run without a valid confirmation_token from a matching quote, so Grok can never mail something as its first move. Live sends return a Stripe payment link for you to approve; sandbox: true completes instantly, free, mailing nothing.
• get_letter_status — read-only tracking: screening → printing → mailed → delivered.

Sandbox first: a safe walkthrough

Once the connector is added, try this prompt verbatim:

"Send a one-page test letter to Maria Alvarez, 1 Main St, Richmond VA 23220
in sandbox mode. Show me the price before you send anything."

Grok should call quote_letter first and show you an price with a confirmation_token, then call send_letter with that token and sandbox: true. The sandbox order runs the entire real pipeline — address checks, content screening, simulated printing and tracking — but nothing is printed, mailed, or charged. When you are ready for a real letter, drop the word “sandbox” and approve the Stripe payment link Grok hands back.

Connect it (xAI API)

If you are building on the xAI API rather than chatting on grok.com, remote MCP tools attach per-request. Native SDK:

# xAI SDK — attach the paperplane MCP server to a chat
from xai_sdk import Client
from xai_sdk.tools import mcp

client = Client()
chat = client.chat.create(
    model="grok-4",
    tools=[mcp(server_url="https://sendpaperplane.com/api/mcp")],
)

Or with the OpenAI-compatible Responses API:

// OpenAI-compatible Responses API
{
  "model": "grok-4",
  "tools": [
    { "type": "mcp",
      "server_url": "https://sendpaperplane.com/api/mcp",
      "server_label": "paperplane" }
  ],
  "input": "Quote a certified letter to 1 Main St, Richmond VA 23220."
}

xAI manages the MCP connection server-side either way — you never proxy tool calls yourself. Grok’s UI and API for connectors evolve quickly; if a menu name here has drifted, the constant part is the URL: any “add a custom / remote MCP server” option pointed at https://sendpaperplane.com/api/mcp works.

If you would rather not use MCP

The same backend is a plain REST API — POST /v1/quotes, POST /v1/orders, GET /v1/orders/:id — documented on the developer docs. Grok can also just write the curl for you. For the full mechanics of the quote→send confirmation contract, see how AI agents mail letters via MCP, or watch it happen live in the no-signup demo.