> For the complete documentation index, see [llms.txt](https://docs.moderncollections.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.moderncollections.io/mcp-servers/authentication.md).

# Authentication

The MCP server uses the same creditor API keys as the REST API — there are no separate MCP-scoped keys. Set `MC_API_KEY` to a key of the form `ca_<prefix>_<secret>` before starting the server.

```bash
export MC_API_KEY=ca_a3f8c0d1_yourSecretHere
mc-api-mcp
```

The key is read from the server's process environment (never from tool arguments, so it stays out of MCP client config that may be logged). It is never written to stdio, never included in tool error messages, and excluded from all internal `repr()` and log output.

## Key format

| Field             | Description                                            |
| ----------------- | ------------------------------------------------------ |
| `MC_API_KEY`      | Creditor API key — same key used for direct REST calls |
| `MC_API_ENV`      | Environment alias: `demo` or `prod`                    |
| `MC_API_BASE_URL` | Explicit base URL — overrides `MC_API_ENV` when set    |

See [API key management](https://github.com/knollmeyersam-dot/MC-Docs/blob/main/help-center/account-and-settings/api-keys.md) for how to generate and rotate keys.

## See also

* [MCP overview](/mcp-servers/overview.md)
* [REST API authentication](/getting-started/authentication.md)


---

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