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

# Authentication and billing

> Create and protect the Context Protocol API key used to access Meridian.

Meridian is accessed publicly through Context Protocol. Context supplies authentication, marketplace discovery, billing, spend controls, and the official remote MCP endpoint.

## Create a key

Create an API key at [ctxprotocol.com/settings](https://ctxprotocol.com/settings). Production keys begin with `sk_live_`.

```bash theme={null}
export CONTEXT_API_KEY="sk_live_YOUR_KEY"
```

## Key handling

* Keep the key on a backend, server, or trusted local agent.
* Never expose it in browser JavaScript.
* Never place it in a URL or query string.
* Never commit it to source control.
* Rotate the key immediately if it appears in logs or screenshots.

## Billing modes

| Mode    | Context method           | Best for                                                                       |
| ------- | ------------------------ | ------------------------------------------------------------------------------ |
| Query   | `client.query.run()`     | Natural-language questions, grounding, managed orchestration                   |
| Execute | `client.tools.execute()` | Exact method calls, raw structured output, explicit per-call spending controls |

Execute availability is method-specific. Discover Meridian with `mode="execute"` before relying on direct execution. If a method is not Execute-eligible, use pinned Query mode.

<Note>
  Pricing and wallet settlement are owned by Context Protocol. Meridian documentation does not override the current price shown by Context discovery or execution responses.
</Note>