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

# API Parameters

This page documents the configuration parameters you can pass to the Michi chat completions endpoint (`POST /chat/completions`).

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### Model

* **Key**: `model`
* **Type**: `string`
* **Requirement**: `Required`
* **Description**: The ID of the model to use. You can specify a specific model key (e.g., `"openai/gpt-4o-mini"`, `"claude/claude-3-5-sonnet"`) or use `"auto"` to let the Semantic Routing Engine dynamically choose the best model.

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### Messages

* **Key**: `messages`
* **Type**: `array of objects`
* **Requirement**: `Required`
* **Description**: A list of messages comprising the conversation so far. Each message object contains:
  * `role` (string): `"system"`, `"user"`, or `"assistant"`.
  * `content` (string): The text content of the message.

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### Temperature

* **Key**: `temperature`
* **Type**: `float` (0.0 to 2.0)
* **Default**: `1.0`
* **Description**: Influences the creativity and variety of the model's responses. Lower values (like `0.2`) make responses more focused, predictable, and deterministic. Higher values (like `1.5`) encourage more creative, diverse, and less typical output. At `0.0`, the model always gives the same response for a given input.

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### Max Tokens

* **Key**: `max_tokens`
* **Type**: `integer`
* **Default**: `500` (defaults to 500 at the gateway layer if omitted)
* **Description**: The maximum number of tokens to generate in the chat completion. The total length of input tokens and generated tokens is limited by the model's context length.

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### Stream

* **Key**: `stream`
* **Type**: `boolean`
* **Default**: `false`
* **Description**: If set to `true`, token chunks will be sent as data-only server-sent events (SSE) as they become available, instead of waiting for the full response to compile.

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### Top P

* **Key**: `top_p`
* **Type**: `float` (0.0 to 1.0)
* **Default**: `1.0`
* **Description**: An alternative to sampling with temperature, called nucleus sampling. The model considers the results of the tokens with `top_p` probability mass. For example, `0.1` means only the tokens comprising the top 10% probability mass are considered.

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### Presence Penalty

* **Key**: `presence_penalty`
* **Type**: `float` (-2.0 to 2.0)
* **Default**: `0.0`
* **Description**: Penalizes new tokens based on whether they appear in the text so far. Positive values increase the model's likelihood to talk about new topics.

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### Frequency Penalty

* **Key**: `frequency_penalty`
* **Type**: `float` (-2.0 to 2.0)
* **Default**: `0.0`
* **Description**: Penalizes new tokens based on their existing frequency in the text so far. Decreases the model's likelihood to repeat the exact same phrases.