# Connect Erlin to an MCP client

> Connect the Erlin MCP server to Claude with OAuth in about a minute, or with an Erlin API key in Claude Code or a config file.

<Frame caption="Add the server, then sign in">
  <img src="/docs/mcp/connect/01-connect.png" alt="Your AI client, the Erlin server address, then sign in" />
</Frame>

Connect Erlin to Claude by adding `https://mcp.erlin.ai/mcp` as a custom connector and signing in to Erlin. This OAuth method takes about a minute and needs no key, terminal or config file. Claude Code and config files connect with an Erlin API key instead.

MCP comes with the Standard, Pro and Enterprise plans. Free and Starter do not include it. See [Plans and billing](https://www.erlin.ai/docs/settings/plans-and-billing). The MCP key is separate from provider keys such as OpenRouter in [API keys](https://www.erlin.ai/docs/settings/api-keys).

## 1. Add the server

To connect with OAuth (recommended) in the [Claude Desktop app](https://claude.ai/download):

<Steps>
  <Step title="Open Settings in Claude Desktop">
    Click your profile icon in the bottom-left corner, then click **Settings**.
  </Step>
  <Step title="Open Connectors">
    In Settings, click **Connectors**.
  </Step>
  <Step title="Add a custom connector">
    Click **Add custom connector** and paste this URL:

    ```
    https://mcp.erlin.ai/mcp
    ```
  </Step>
  <Step title="Sign in and approve">
    Click **Connect**. Your browser opens Erlin. Sign in, review the request to access your Erlin account, and click **Approve**.
  </Step>
</Steps>

If your plan does not include MCP, the Erlin sign-in screen says "Your plan doesn't include MCP" and shows **Upgrade** and **Deny** instead of **Approve**.

## 2. Keep credentials separate from conversation text

Claude Code and the config-file method send an Erlin API key in the `X-API-Key` header. Your key lives in **Settings > MCP** in Erlin, which only the account owner sees. Erlin creates the key the first time you open the section and shows it in full once: copy it right away, because afterwards Erlin shows only its start. Erlin API keys start with `ek_live_`.

To replace a lost or exposed key, click **New key**, then **Make a new key**. The old key stops working straight away, so update every client that uses it. Never paste a key into a chat message or a support request.

**Claude Code.** Run this in your terminal, with your key in place of `<your key>`:

```bash
claude mcp add --transport http erlin-ai https://mcp.erlin.ai/mcp --header "X-API-Key: <your key>"
```

**Config file.** You can add Erlin to Claude Desktop by editing its config file. This method runs the `mcp-remote` bridge, so it needs [Node.js](https://nodejs.org) installed. Open the config file:

- **macOS**: `~/Library/Application Support/Claude/claude_desktop_config.json`
- **Windows**: `%APPDATA%\Claude\claude_desktop_config.json`

Add Erlin, with your key in place of `<your key>`, then save the file and restart Claude Desktop:

```json claude_desktop_config.json
{
  "mcpServers": {
    "erlin-ai": {
      "command": "npx",
      "args": ["mcp-remote", "https://mcp.erlin.ai/mcp", "--header", "X-API-Key:${ERLIN_API_KEY}"],
      "env": { "ERLIN_API_KEY": "<your key>" }
    }
  }
}
```

## 3. Confirm the connection

Erlin appears in your connectors list. Ask Claude "What websites do I have in Erlin?" Claude uses `erlin_list_websites` to list the websites in your account. If you track more than one, name the website you mean before asking about its results.

<Frame caption="Choose the website before asking about its results.">
  <img src="/docs/mcp/connect/02-pick-site.png" alt="A list of websites with one picked, then a question about it" />
</Frame>

## Troubleshoot the failed step

| Problem | Fix |
|---|---|
| "Server disconnected" | Quit Claude Desktop completely (Cmd+Q on Mac, Alt+F4 on Windows) and reopen it. |
| "Your Erlin session has expired" | In Claude Desktop, go to **Settings > Connectors**, find Erlin, and reconnect. Sign in again when the browser opens. |
| "Invalid or expired API key" | Copy your current key from **Settings > MCP** in Erlin, or click **New key** to make a new one, then update your command or config file. |
| "Your plan doesn't include MCP access" | MCP comes with Standard, Pro and Enterprise. See [Plans and billing](https://www.erlin.ai/docs/settings/plans-and-billing). |
| "Rate limit exceeded" | Wait the number of seconds Claude reports, then ask again. See [credits and limits](https://www.erlin.ai/docs/mcp/credits-and-limits). |
| Sign-in page does not load | Check that you can open app.erlin.ai in your browser, then reconnect. |
| Erlin tools do not appear in Claude | Check the connector URL is `https://mcp.erlin.ai/mcp`, then restart Claude Desktop. |

Still stuck? Contact [Support](https://www.erlin.ai/docs/settings/support) or email help@erlin.ai with the error and time, but never your key.