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

# MessagesRequestMetadata

## Fields

| Field     | Type                     | Required             | Description |
| --------- | ------------------------ | -------------------- | ----------- |
| `user_id` | *OptionalNullable\[str]* | :heavy\_minus\_sign: | N/A         |