> ## Documentation Index
> Fetch the complete documentation index at: https://openrouter-d02e98a0-mintlify-7021d5f4.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# ChatFormatGrammarConfig - Python SDK

> ChatFormatGrammarConfig method reference

<Warning>
  The Python SDK and docs are currently in beta.
  Report issues on [GitHub](https://github.com/OpenRouterTeam/python-sdk/issues).
</Warning>

Custom grammar response format

## Fields

| Field     | Type                                                                                                               | Required             | Description                        | Example                |
| --------- | ------------------------------------------------------------------------------------------------------------------ | -------------------- | ---------------------------------- | ---------------------- |
| `grammar` | *str*                                                                                                              | :heavy\_check\_mark: | Custom grammar for text generation | root ::= "yes" \| "no" |
| `type`    | [components.ChatFormatGrammarConfigType](/client-sdks/python/api-reference/components/chatformatgrammarconfigtype) | :heavy\_check\_mark: | N/A                                |                        |