> For the complete documentation index, see [llms.txt](https://docs.ionos.com/cloud/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ionos.com/cloud/ai/mcp-server/configuration/environment-variables.md).

# Environment Variables

All MCP server configuration is done through environment variables passed in your AI client's MCP server configuration.

## Variables

| Variable               | Required | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| ---------------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `IONOS_TOKEN`          | Yes      | <code class="expression">space.vars.ionos\_cloud\_api</code> token. Authenticates all Compute Engine, Managed Kubernetes, Cloud DNS, Billing, Certificate Manager, <code class="expression">ionos\_cloud\_object\_storage</code>, and Activity Log API requests.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| `IONOS_S3_ACCESS_KEY`  | No       | Object Storage access key. Required for Object Storage data-plane tools (listing objects, reading bucket configuration).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| `IONOS_S3_SECRET_KEY`  | No       | Object Storage secret key. Required together with `IONOS_S3_ACCESS_KEY`.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| `IONOS_MCP_LOAD_MODE`  | No       | <p>Controls how the server registers tools at startup. <strong>Accepted values:</strong><br><code>eager</code>: Registers all tools immediately. This is the default.<br><code>lazy</code>: Registers only the 45 always-on tools and 2 loader sentinels; Compute and Object Storage register on demand.<br><code>dynamic</code> (alias <code>search</code>): Registers only the three meta-tools <code>ionos\_search\_tools</code>, <code>ionos\_describe\_tools</code>, and <code>ionos\_call\_tool</code>; the assistant discovers and calls the rest of the catalog through them. Intended for clients with a hard tool cap, such as Cursor.<br>For more information, see <a href="/cloud/ai/mcp-server/configuration/selective-tool-loading.md"><mark style="color:blue;">Selective Tool Loading</mark></a>.</p> |
| `IONOS_MCP_TOOL_SCOPE` | No       | <p>Controls whether write tools are registered. The server is read-only unless you set this variable. <strong>Accepted values:</strong><br><code>read</code>: read-only tools only. This is the default, and the fallback for any unrecognised value.<br><code>write</code>: also registers <code>create\_*</code>, <code>update\_*</code>, and non-disruptive actions.<br><code>destructive</code>: also registers <code>delete\_\*</code> and disruptive actions. Implies <code>write</code>.<br>For more information, see <a href="/cloud/ai/mcp-server/configuration/write-operations.md"><mark style="color:blue;">Write Operations</mark></a>.</p>                                                                                                                                                              |
| `IONOS_MCP_TRANSPORT`  | No       | <p>Selects the MCP wire transport. <strong>Accepted values:</strong><br><code>stdio</code>: the server runs as a local subprocess and exchanges messages over standard input and output. This is the default, and the fallback for any unrecognised value.<br><code>http</code>: the server listens on <code>IONOS\_MCP\_HTTP\_ADDR</code> and serves the Streamable HTTP transport.<br>For more information, see <a href="/cloud/ai/mcp-server/configuration/transport.md"><mark style="color:blue;">Transport</mark></a>.</p>                                                                                                                                                                                                                                                                                       |
| `IONOS_MCP_HTTP_ADDR`  | No       | Listen address for the HTTP transport, for example `127.0.0.1:8080` or `:8080`. Defaults to `127.0.0.1:8080`, which accepts local connections only. Ignored when the transport is `stdio`.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |

## Command-line flags

The same two settings are also available as flags, which take precedence over the environment variables: `--transport <stdio|http>` and `--http-addr <address>`. Use the flags when you start the server yourself rather than letting an AI client start it. For more information, see [<mark style="color:blue;">Transport</mark>](/cloud/ai/mcp-server/configuration/transport.md).

## Example

```json
{
  "mcpServers": {
    "ionoscloud": {
      "command": "/path/to/ionoscloud-mcp",
      "env": {
        "IONOS_TOKEN": "your-api-token",
        "IONOS_S3_ACCESS_KEY": "your-access-key",
        "IONOS_S3_SECRET_KEY": "your-secret-key"
      }
    }
  }
}
```


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