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

# synthesize_speech

> Generate an MP3 speech sample with Rime TTS via the MCP server, rendered in an inline audio player.

Generate an MP3 speech sample from text. With no arguments, the tool plays a default sample in the demo voice (`lyra` on **Coda**, Rime's flagship model). Choose a `speaker` and `modelId` from [`list_voices`](/mcp-reference/list-voices) and [`get_voice_details`](/mcp-reference/get-voice-details).

**API key:** Required. See [Authentication](/mcp-reference/authentication). Samples consume credits like any other API request, so keep sample text short.

## Parameters

| Parameter       | Type    | Required | Default           | Description                                                                                                                                                                |
| --------------- | ------- | -------- | ----------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `text`          | string  | No       | A short demo line | Text to synthesize (max 2,000 characters)                                                                                                                                  |
| `speaker`       | string  | No       | `lyra`            | Voice name from [`list_voices`](/mcp-reference/list-voices)                                                                                                                |
| `modelId`       | string  | No       | `coda`            | Model ID: `coda` or `mistv3`                                                                                                                                               |
| `language`      | string  | No       | None              | Sent as `lang` only if provided (e.g. `eng`, the value from [`get_voice_details`](/mcp-reference/get-voice-details)). Omit to let Rime infer the language from the speaker |
| `include_audio` | boolean | No       | `false`           | Also return the audio as a standard MCP audio content block (base64), for hosts that play audio natively. Adds the audio to the model's context                            |

## Returns

The tool delivers audio three ways so it plays regardless of the host: an inline player in UI hosts, a short-lived play URL (`structuredContent.audioUrl`) for terminal hosts, and an optional audio content block. See [Playing audio](/mcp-reference/audio).

## Example

Ask your assistant:

```
Play me a sample of the astra voice saying "Thanks for calling, how can I help?"
```

## Related

* [Playing audio](/mcp-reference/audio): how samples reach your speakers in each host
* [Models](/docs/models): compare Coda, Mist v3, and Mist v2
* [Streaming APIs](/docs/streaming): production synthesis