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Connect Stable to AI apps using MCP

Stable’s MCP server gives your AI assistants like Claude, ChatGPT, and Cursor secure access to your Stable account.

Overview

Stable’s MCP server gives your AI assistants like Claude, ChatGPT, and Cursor secure access to your Stable account. Model Context Protocol (MCP) is an open standard that lets AI agents connect to outside apps and tools.

The Stable MCP server is available at https://mcp.usestable.com/mcp. An x-api-key header with a valid API key from your account is required.

What you can do with the Stable MCP

Your AI assistant can read your account data, help organize your mail, and take other actions within Stable. If you have other apps connected, you can build automations that can connect data in Stable with outside systems.

Stable resource

What your assistant can do

Mail items

List, filter, and read mail, including sender, recipients, document scans, summaries, checks, extracted data, and forwarding, deposit, and shred status

Tags and teams on mail

Assign or remove tags and teams on mail items

Locations

List your addresses and see their types

Company

Read your company details

Your agent can also help you explore the Stable API. It can list and search endpoints and read endpoint documentation. It can be a useful pair programmer when you're building on the API. For more information about Stable's API, see https://docs.usestable.com.

See the example prompts below for more ideas on using the MCP in your workflows.

Guided setup in Stable

The Stable dashboard includes setup instructions for popular AI apps and tools.

  1. In Stable, go to Settings → API keys.

  2. Select Connect AI app, then choose your AI tool.

  3. Follow the steps shown.

Prefer to set up your AI tool by hand? Select Create key instead, then follow the instructions for your tool below.

Manual setup

If your AI app isn’t listed in the guided setup, or if you prefer to manually set it up, follow these instructions.

Replace YOUR_API_KEY with your Stable API key where it appears in each example. You can create an API key in the dashboard under Settings → API keys.

Keep your key safe. An API key has the same access to your account that you do. If you lose it, create a new one. Removing your user revokes your keys automatically.

Claude (Web)

You need to be an account administrator to add a custom connector. Claude may require a paid plan.

  1. In Claude, open Settings → Connectors and select Add custom connector.

  2. Add the MCP Server details

    1. Name: Stable

    2. URL: https://mcp.usestable.com/mcp

    3. Click Continue

  3. Set the authentication and your API key

    1. Authentication: select No sign-in.

    2. Request headers: select Add header, enter x-api-key as the name and your Stable API key as the value. Leave Required checked.

    3. Click Add

  4. Select Connect to enable the connector.

  5. On a Team or Enterprise plan, each member will need to select Connect under Customize → Connectors.

Claude (Desktop)

If you've already added Stable as a custom connector in your Claude organization, it's already available in Claude Desktop.

To run it from your own device instead, use the config file below. The local setup uses mcp-remote, a small open-source bridge that runs on your computer. You need Node.js installed.

  1. Open your Claude Desktop config file:

    • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

    • Windows: %APPDATA%\Claude\claude_desktop_config.json

  2. Add Stable to the mcpServers block:

    {
      "mcpServers": {
        "stable": {
          "command": "npx",
          "args": ["-y", "mcp-remote", "https://mcp.usestable.com/mcp", "--header", "x-api-key:${STABLE_API_KEY}"],
          "env": { "STABLE_API_KEY": "YOUR_API_KEY" }
        }
      }
    }

  3. Quit and reopen Claude Desktop.

ChatGPT (Web)

ChatGPT connects to Stable using a custom MCP server. You may need to enable Developer mode in your ChatGPT organization.

  1. Create your API key in the Stable Dashboard

  2. Navigate to https://chatgpt.com/plugins and click Add → Create custom MCP server

  3. Add the MCP server details

    1. Name: Stable

    2. Connection: https://mcp.usestable.com/mcp?x-api-key=YOUR_API_KEY

    3. Authentication: No authentication.

    4. Check the box I understand and want to continue

    5. Click Create as a plugin.

  4. Click Connect Stable when prompted

Muse

Muse from Meta can be configured as a custom connector via chat. Muse will set up a custom connector, then it will ask for your Stable API key. You can create in the Stable dashboard under Settings → API keys.

  1. Paste the following prompt into any chat with Muse:

    Connect to Stable. Use the OpenAPI spec at
    https://docs.usestable.com/openapi/swagger.json,
    the base URL https://api.usestable.com, and the x-api-key header.

  2. Click Connect when prompted, then review the prompt and enter your API key.

  3. Muse might ask for your permission to access the Stable API. Select Always Allow to allow it to run in the background.
    ​

Other AI apps

Any tool that supports remote MCP servers works with Stable:

  • URL: https://mcp.usestable.com/mcp

  • Transport: HTTP (Streamable HTTP)

  • Header: x-api-key: YOUR_API_KEY

If your tool can't send custom headers, put the key in the URL instead: https://mcp.usestable.com/mcp?x-api-key=YOUR_API_KEY. This URL works like a password, so keep it private.

Example prompts

Once you're connected, ask about your mail the way you'd ask a colleague. A few ideas to start:

  • "Which checks came in this month, and what's the total?"

  • "What mail arrived at our Stable address this week?"

  • "Summarize the letters we received from the IRS in the last 30 days."

  • "Which Stable mail items are still waiting to be scanned?"

  • "Tag every mail item from {Sender} with 'Legal.'"

  • "Assign all mail addressed to {Recipient} to the Finance team."

  • "Write a Python script that pulls yesterday's mail items from Stable and saves them to a CSV."

  • "Copy the scans of any Stable mail from the IRS into Google Drive" (requires a connected Google Workspace or Google Drive account).

Manage access

Use a separate API key for each tool you connect. You can then see which tools are active and revoke one without breaking the others. Actions the MCP takes against your mail will be labeled as “API” in the mail item activity logs.

To revoke a key, go to Settings → API keys, open the menu next to the key, and select Revoke.

Connect MCP to Stable sandbox accounts

If you use Stable’s sandbox to test your integrations, you can use https://mcp.dev.usestable.com/mcp as the MCP URL. This requires a sandbox-specific API key.

Troubleshooting

Problem

Fix

Your assistant says it can't access Stable

Check that the key is set, in the x-api-key header or the URL, and that it hasn't been revoked. Create a new key if needed.

Stable doesn't appear in your tool

Restart the tool after editing its config file. With coding agents, run /mcp or the equivalent to check the connection.

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