> ## 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.

# ModelArchitecture

Model architecture information

## Fields

| Field               | Type                                                                                                            | Required             | Description                      | Example    |
| ------------------- | --------------------------------------------------------------------------------------------------------------- | -------------------- | -------------------------------- | ---------- |
| `input_modalities`  | List\[[components.InputModality](../components/inputmodality.mdx)]                                              | :heavy\_check\_mark: | Supported input modalities       |            |
| `instruct_type`     | [OptionalNullable\[components.ModelArchitectureInstructType\]](../components/modelarchitectureinstructtype.mdx) | :heavy\_minus\_sign: | Instruction format type          | chatml     |
| `modality`          | *Nullable\[str]*                                                                                                | :heavy\_check\_mark: | Primary modality of the model    | text->text |
| `output_modalities` | List\[[components.OutputModality](../components/outputmodality.mdx)]                                            | :heavy\_check\_mark: | Supported output modalities      |            |
| `tokenizer`         | [Optional\[components.ModelGroup\]](../components/modelgroup.mdx)                                               | :heavy\_minus\_sign: | Tokenizer type used by the model | GPT        |