> ## Documentation Index
> Fetch the complete documentation index at: https://radiusbrowser.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Claude API key

> Use an Anthropic API key stored securely by Radius.

| Item          | Behavior                                                       |
| ------------- | -------------------------------------------------------------- |
| Use for       | A first-party Anthropic API key                                |
| Configuration | A Radius-owned isolated `CLAUDE_CONFIG_DIR`                    |
| Credentials   | `ANTHROPIC_API_KEY`                                            |
| Isolation     | Ambient Claude and cloud-provider credentials do not take over |

## How it works

1. Select **API Key** and save your Anthropic key.
2. Radius stores the key in encrypted credential storage.
3. Radius removes ambient Anthropic, Bedrock, Vertex AI, and Foundry
   authentication variables, then supplies the saved key.
4. Claude discovers and runs models with the isolated configuration.

Project and local settings can still affect agent behavior. They cannot replace
the selected authentication method.

<Warning>
  Use [Claude CLI](/docs/agents/claude/cli) for AWS Bedrock. The API-key method is
  specifically for an Anthropic API key.
</Warning>