---
summary: "Text-to-speech (TTS) for outbound replies"
read_when:
  - Enabling text-to-speech for replies
  - Configuring TTS providers or limits
  - Using /tts commands
title: "Text-to-speech"
---

OpenClaw can convert outbound replies into audio using Azure Speech, ElevenLabs, Google Gemini, Gradium, Inworld, Local CLI, Microsoft, MiniMax, OpenAI, Volcengine, Vydra, xAI, or Xiaomi MiMo.
It works anywhere OpenClaw can send audio.

## Supported services

- **Azure Speech** (primary or fallback provider; uses the Azure AI Speech REST API)
- **ElevenLabs** (primary or fallback provider)
- **Google Gemini** (primary or fallback provider; uses Gemini API TTS)
- **Gradium** (primary or fallback provider; supports voice-note and telephony output)
- **Inworld** (primary or fallback provider; uses the Inworld streaming TTS API)
- **Local CLI** (primary or fallback provider; runs a configured local TTS command)
- **Microsoft** (primary or fallback provider; current bundled implementation uses `node-edge-tts`)
- **MiniMax** (primary or fallback provider; uses the T2A v2 API)
- **OpenAI** (primary or fallback provider; also used for summaries)
- **Volcengine** (primary or fallback provider; uses the BytePlus Seed Speech HTTP API)
- **Vydra** (primary or fallback provider; shared image, video, and speech provider)
- **xAI** (primary or fallback provider; uses the xAI TTS API)
- **Xiaomi MiMo** (primary or fallback provider; uses MiMo TTS through Xiaomi chat completions)

### Microsoft speech notes

The bundled Microsoft speech provider currently uses Microsoft Edge's online
neural TTS service via the `node-edge-tts` library. It's a hosted service (not
local), uses Microsoft endpoints, and does not require an API key.
`node-edge-tts` exposes speech configuration options and output formats, but
not all options are supported by the service. Legacy config and directive input
using `edge` still works and is normalized to `microsoft`.

Because this path is a public web service without a published SLA or quota,
treat it as best-effort. If you need guaranteed limits and support, use OpenAI
or ElevenLabs.

## Optional keys

If you want Azure Speech, ElevenLabs, Google Gemini, Gradium, Inworld, MiniMax, OpenAI, Volcengine, Vydra, xAI, or Xiaomi MiMo:

- `AZURE_SPEECH_KEY` plus `AZURE_SPEECH_REGION` (also accepts
  `AZURE_SPEECH_API_KEY`, `SPEECH_KEY`, and `SPEECH_REGION`)
- `ELEVENLABS_API_KEY` (or `XI_API_KEY`)
- `GEMINI_API_KEY` (or `GOOGLE_API_KEY`)
- `GRADIUM_API_KEY`
- `INWORLD_API_KEY`
- `MINIMAX_API_KEY`; MiniMax TTS also accepts Token Plan auth via
  `MINIMAX_OAUTH_TOKEN`, `MINIMAX_CODE_PLAN_KEY`, or
  `MINIMAX_CODING_API_KEY`
- `OPENAI_API_KEY`
- `VOLCENGINE_TTS_API_KEY` (or `BYTEPLUS_SEED_SPEECH_API_KEY`);
  legacy AppID/token auth also accepts `VOLCENGINE_TTS_APPID` and
  `VOLCENGINE_TTS_TOKEN`
- `VYDRA_API_KEY`
- `XAI_API_KEY`
- `XIAOMI_API_KEY`

Local CLI and Microsoft speech do **not** require an API key.

If multiple providers are configured, the selected provider is used first and the others are fallback options.
Auto-summary uses the configured `summaryModel` (or `agents.defaults.model.primary`),
so that provider must also be authenticated if you enable summaries.

## Service links

- [OpenAI Text-to-Speech guide](https://platform.openai.com/docs/guides/text-to-speech)
- [OpenAI Audio API reference](https://platform.openai.com/docs/api-reference/audio)
- [Azure Speech REST text-to-speech](https://learn.microsoft.com/azure/ai-services/speech-service/rest-text-to-speech)
- [Azure Speech provider](/providers/azure-speech)
- [ElevenLabs Text to Speech](https://elevenlabs.io/docs/api-reference/text-to-speech)
- [ElevenLabs Authentication](https://elevenlabs.io/docs/api-reference/authentication)
- [Gradium](/providers/gradium)
- [Inworld TTS API](https://docs.inworld.ai/tts/tts)
- [MiniMax T2A v2 API](https://platform.minimaxi.com/document/T2A%20V2)
- [Volcengine TTS HTTP API](/providers/volcengine#text-to-speech)
- [Xiaomi MiMo speech synthesis](/providers/xiaomi#text-to-speech)
- [node-edge-tts](https://github.com/SchneeHertz/node-edge-tts)
- [Microsoft Speech output formats](https://learn.microsoft.com/azure/ai-services/speech-service/rest-text-to-speech#audio-outputs)
- [xAI Text to Speech](https://docs.x.ai/developers/rest-api-reference/inference/voice#text-to-speech-rest)

## Is it enabled by default?

No. Auto‑TTS is **off** by default. Enable it in config with
`messages.tts.auto` or locally with `/tts on`.

When `messages.tts.provider` is unset, OpenClaw picks the first configured
speech provider in registry auto-select order.

## Config

TTS config lives under `messages.tts` in `openclaw.json`.
Full schema is in [Gateway configuration](/gateway/configuration).

### Minimal config (enable + provider)

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "elevenlabs",
    },
  },
}
```

### OpenAI primary with ElevenLabs fallback

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "openai",
      summaryModel: "openai/gpt-4.1-mini",
      modelOverrides: {
        enabled: true,
      },
      providers: {
        openai: {
          apiKey: "openai_api_key",
          baseUrl: "https://api.openai.com/v1",
          model: "gpt-4o-mini-tts",
          voice: "alloy",
        },
        elevenlabs: {
          apiKey: "elevenlabs_api_key",
          baseUrl: "https://api.elevenlabs.io",
          voiceId: "voice_id",
          modelId: "eleven_multilingual_v2",
          seed: 42,
          applyTextNormalization: "auto",
          languageCode: "en",
          voiceSettings: {
            stability: 0.5,
            similarityBoost: 0.75,
            style: 0.0,
            useSpeakerBoost: true,
            speed: 1.0,
          },
        },
      },
    },
  },
}
```

### Azure Speech primary

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "azure-speech",
      providers: {
        "azure-speech": {
          // apiKey falls back to AZURE_SPEECH_KEY.
          // region falls back to AZURE_SPEECH_REGION.
          voice: "en-US-JennyNeural",
          lang: "en-US",
          outputFormat: "audio-24khz-48kbitrate-mono-mp3",
          voiceNoteOutputFormat: "ogg-24khz-16bit-mono-opus",
        },
      },
    },
  },
}
```

Azure Speech uses a Speech resource key, not an Azure OpenAI key. Resolution
order is `messages.tts.providers.azure-speech.apiKey` ->
`AZURE_SPEECH_KEY` -> `AZURE_SPEECH_API_KEY` -> `SPEECH_KEY`, plus
`messages.tts.providers.azure-speech.region` -> `AZURE_SPEECH_REGION` ->
`SPEECH_REGION` for the region. New config should use `azure-speech`; `azure`
is accepted as a provider alias.

### Microsoft primary (no API key)

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "microsoft",
      providers: {
        microsoft: {
          enabled: true,
          voice: "en-US-MichelleNeural",
          lang: "en-US",
          outputFormat: "audio-24khz-48kbitrate-mono-mp3",
          rate: "+10%",
          pitch: "-5%",
        },
      },
    },
  },
}
```

### MiniMax primary

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "minimax",
      providers: {
        minimax: {
          apiKey: "minimax_api_key",
          baseUrl: "https://api.minimax.io",
          model: "speech-2.8-hd",
          voiceId: "English_expressive_narrator",
          speed: 1.0,
          vol: 1.0,
          pitch: 0,
        },
      },
    },
  },
}
```

MiniMax TTS auth resolution is `messages.tts.providers.minimax.apiKey`, then
stored `minimax-portal` OAuth/token profiles, then Token Plan environment keys
(`MINIMAX_OAUTH_TOKEN`, `MINIMAX_CODE_PLAN_KEY`,
`MINIMAX_CODING_API_KEY`), then `MINIMAX_API_KEY`. When no explicit TTS
`baseUrl` is set, OpenClaw can reuse the configured `minimax-portal` OAuth
host for Token Plan speech.

### Google Gemini primary

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "google",
      providers: {
        google: {
          apiKey: "gemini_api_key",
          model: "gemini-3.1-flash-tts-preview",
          voiceName: "Kore",
        },
      },
    },
  },
}
```

Google Gemini TTS uses the Gemini API key path. A Google Cloud Console API key
restricted to the Gemini API is valid here, and it is the same style of key used
by the bundled Google image-generation provider. Resolution order is
`messages.tts.providers.google.apiKey` -> `models.providers.google.apiKey` ->
`GEMINI_API_KEY` -> `GOOGLE_API_KEY`.

### Inworld primary

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "inworld",
      providers: {
        inworld: {
          apiKey: "inworld_api_key",
          baseUrl: "https://api.inworld.ai",
          voiceId: "Sarah",
          modelId: "inworld-tts-1.5-max",
          temperature: 0.8,
        },
      },
    },
  },
}
```

The `apiKey` value must be the Base64-encoded credential string copied
verbatim from the Inworld dashboard (Workspace > API Keys). The provider
sends it as `Authorization: Basic <apiKey>` without any additional
encoding, so do not pass a raw bearer token and do not Base64-encode it
yourself. The key falls back to the `INWORLD_API_KEY` env var. See
[Inworld provider](/providers/inworld) for full setup.

### Volcengine primary

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "volcengine",
      providers: {
        volcengine: {
          apiKey: "byteplus_seed_speech_api_key",
          resourceId: "seed-tts-1.0",
          voice: "en_female_anna_mars_bigtts",
          speedRatio: 1.0,
        },
      },
    },
  },
}
```

Volcengine TTS uses the BytePlus Seed Speech API key from the Speech Console,
not the OpenAI-compatible `VOLCANO_ENGINE_API_KEY` used for Doubao model
providers. Resolution order is `messages.tts.providers.volcengine.apiKey` ->
`VOLCENGINE_TTS_API_KEY` -> `BYTEPLUS_SEED_SPEECH_API_KEY`. Legacy AppID/token
auth still works through `messages.tts.providers.volcengine.appId` / `token` or
`VOLCENGINE_TTS_APPID` / `VOLCENGINE_TTS_TOKEN`. Voice-note targets request
provider-native `ogg_opus`; normal audio-file targets request `mp3`.

### xAI primary

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "xai",
      providers: {
        xai: {
          apiKey: "xai_api_key",
          voiceId: "eve",
          language: "en",
          responseFormat: "mp3",
          speed: 1.0,
        },
      },
    },
  },
}
```

xAI TTS uses the same `XAI_API_KEY` path as the bundled Grok model provider.
Resolution order is `messages.tts.providers.xai.apiKey` -> `XAI_API_KEY`.
Current live voices are `ara`, `eve`, `leo`, `rex`, `sal`, and `una`; `eve` is
the default. `language` accepts a BCP-47 tag or `auto`.

### Xiaomi MiMo primary

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "xiaomi",
      providers: {
        xiaomi: {
          apiKey: "xiaomi_api_key",
          baseUrl: "https://api.xiaomimimo.com/v1",
          model: "mimo-v2.5-tts",
          voice: "mimo_default",
          format: "mp3",
          style: "Bright, natural, conversational tone.",
        },
      },
    },
  },
}
```

Xiaomi MiMo TTS uses the same `XIAOMI_API_KEY` path as the bundled Xiaomi model
provider. The speech provider id is `xiaomi`; `mimo` is accepted as an alias.
The target text is sent as the assistant message, matching Xiaomi's TTS
contract. Optional `style` is sent as a user instruction and is not spoken.

### OpenRouter primary

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "openrouter",
      providers: {
        openrouter: {
          apiKey: "openrouter_api_key",
          model: "hexgrad/kokoro-82m",
          voice: "af_alloy",
          responseFormat: "mp3",
        },
      },
    },
  },
}
```

OpenRouter TTS uses the same `OPENROUTER_API_KEY` path as the bundled
OpenRouter model provider. Resolution order is
`messages.tts.providers.openrouter.apiKey` ->
`models.providers.openrouter.apiKey` -> `OPENROUTER_API_KEY`.

### Local CLI primary

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "tts-local-cli",
      providers: {
        "tts-local-cli": {
          command: "say",
          args: ["-o", "{{OutputPath}}", "{{Text}}"],
          outputFormat: "wav",
          timeoutMs: 120000,
        },
      },
    },
  },
}
```

Local CLI TTS runs the configured command on the gateway host. `{{Text}}`,
`{{OutputPath}}`, `{{OutputDir}}`, and `{{OutputBase}}` placeholders are
expanded in `args`; if no `{{Text}}` placeholder is present, OpenClaw writes the
spoken text to stdin. `outputFormat` accepts `mp3`, `opus`, or `wav`.
Voice-note targets are transcoded to Ogg/Opus and telephony output is
transcoded to raw 16 kHz mono PCM with `ffmpeg`. The legacy provider alias
`cli` still works, but new config should use `tts-local-cli`.

### Gradium primary

```json5
{
  messages: {
    tts: {
      auto: "always",
      provider: "gradium",
      providers: {
        gradium: {
          apiKey: "gradium_api_key",
          baseUrl: "https://api.gradium.ai",
          voiceId: "YTpq7expH9539ERJ",
        },
      },
    },
  },
}
```

### Disable Microsoft speech

```json5
{
  messages: {
    tts: {
      providers: {
        microsoft: {
          enabled: false,
        },
      },
    },
  },
}
```

### Custom limits + prefs path

```json5
{
  messages: {
    tts: {
      auto: "always",
      maxTextLength: 4000,
      timeoutMs: 30000,
      prefsPath: "~/.openclaw/settings/tts.json",
    },
  },
}
```

### Only reply with audio after an inbound voice message

```json5
{
  messages: {
    tts: {
      auto: "inbound",
    },
  },
}
```

### Disable auto-summary for long replies

```json5
{
  messages: {
    tts: {
      auto: "always",
    },
  },
}
```

Then run:

```
/tts summary off
```

### Notes on fields

- `auto`: auto‑TTS mode (`off`, `always`, `inbound`, `tagged`).
  - `inbound` only sends audio after an inbound voice message.
  - `tagged` only sends audio when the reply includes `[[tts:key=value]]` directives or a `[[tts:text]]...[[/tts:text]]` block.
- `enabled`: legacy toggle (doctor migrates this to `auto`).
- `mode`: `"final"` (default) or `"all"` (includes tool/block replies).
- `provider`: speech provider id such as `"elevenlabs"`, `"google"`, `"gradium"`, `"inworld"`, `"microsoft"`, `"minimax"`, `"openai"`, `"volcengine"`, `"vydra"`, `"xai"`, or `"xiaomi"` (fallback is automatic).
- If `provider` is **unset**, OpenClaw uses the first configured speech provider in registry auto-select order.
- Legacy `provider: "edge"` config is repaired by `openclaw doctor --fix` and
  rewritten to `provider: "microsoft"`.
- `summaryModel`: optional cheap model for auto-summary; defaults to `agents.defaults.model.primary`.
  - Accepts `provider/model` or a configured model alias.
- `modelOverrides`: allow the model to emit TTS directives (on by default).
  - `allowProvider` defaults to `false` (provider switching is opt-in).
- `providers.<id>`: provider-owned settings keyed by speech provider id.
- Legacy direct provider blocks (`messages.tts.openai`, `messages.tts.elevenlabs`, `messages.tts.microsoft`, `messages.tts.edge`) are repaired by `openclaw doctor --fix`; committed config should use `messages.tts.providers.<id>`.
- Legacy `messages.tts.providers.edge` is also repaired by `openclaw doctor --fix`; committed config should use `messages.tts.providers.microsoft`.
- `maxTextLength`: hard cap for TTS input (chars). `/tts audio` fails if exceeded.
- `timeoutMs`: request timeout (ms).
- `prefsPath`: override the local prefs JSON path (provider/limit/summary).
- `apiKey` values fall back to env vars (`AZURE_SPEECH_KEY`/`AZURE_SPEECH_API_KEY`/`SPEECH_KEY`, `ELEVENLABS_API_KEY`/`XI_API_KEY`, `GEMINI_API_KEY`/`GOOGLE_API_KEY`, `GRADIUM_API_KEY`, `INWORLD_API_KEY`, `MINIMAX_API_KEY`, `OPENAI_API_KEY`, `VYDRA_API_KEY`, `XAI_API_KEY`, `XIAOMI_API_KEY`). Volcengine uses `appId`/`token` instead.
- `providers.azure-speech.apiKey`: Azure Speech resource key (env:
  `AZURE_SPEECH_KEY`, `AZURE_SPEECH_API_KEY`, or `SPEECH_KEY`).
- `providers.azure-speech.region`: Azure Speech region such as `eastus` (env:
  `AZURE_SPEECH_REGION` or `SPEECH_REGION`).
- `providers.azure-speech.endpoint` / `providers.azure-speech.baseUrl`: optional
  Azure Speech endpoint/base URL override.
- `providers.azure-speech.voice`: Azure voice ShortName (default
  `en-US-JennyNeural`).
- `providers.azure-speech.lang`: SSML language code (default `en-US`).
- `providers.azure-speech.outputFormat`: Azure `X-Microsoft-OutputFormat` for
  standard audio output (default `audio-24khz-48kbitrate-mono-mp3`).
- `providers.azure-speech.voiceNoteOutputFormat`: Azure
  `X-Microsoft-OutputFormat` for voice-note output (default
  `ogg-24khz-16bit-mono-opus`).
- `providers.elevenlabs.baseUrl`: override ElevenLabs API base URL.
- `providers.openai.baseUrl`: override the OpenAI TTS endpoint.
  - Resolution order: `messages.tts.providers.openai.baseUrl` -> `OPENAI_TTS_BASE_URL` -> `https://api.openai.com/v1`
  - Non-default values are treated as OpenAI-compatible TTS endpoints, so custom model and voice names are accepted.
- `providers.elevenlabs.voiceSettings`:
  - `stability`, `similarityBoost`, `style`: `0..1`
  - `useSpeakerBoost`: `true|false`
  - `speed`: `0.5..2.0` (1.0 = normal)
- `providers.elevenlabs.applyTextNormalization`: `auto|on|off`
- `providers.elevenlabs.languageCode`: 2-letter ISO 639-1 (e.g. `en`, `de`)
- `providers.elevenlabs.seed`: integer `0..4294967295` (best-effort determinism)
- `providers.minimax.baseUrl`: override MiniMax API base URL (default `https://api.minimax.io`, env: `MINIMAX_API_HOST`).
- `providers.minimax.model`: TTS model (default `speech-2.8-hd`, env: `MINIMAX_TTS_MODEL`).
- `providers.minimax.voiceId`: voice identifier (default `English_expressive_narrator`, env: `MINIMAX_TTS_VOICE_ID`).
- `providers.minimax.speed`: playback speed `0.5..2.0` (default 1.0).
- `providers.minimax.vol`: volume `(0, 10]` (default 1.0; must be greater than 0).
- `providers.minimax.pitch`: integer pitch shift `-12..12` (default 0). Fractional values are truncated before calling MiniMax T2A because the API rejects non-integer pitch values.
- `providers.tts-local-cli.command`: local executable or command string for CLI TTS.
- `providers.tts-local-cli.args`: command arguments; supports `{{Text}}`, `{{OutputPath}}`, `{{OutputDir}}`, and `{{OutputBase}}` placeholders.
- `providers.tts-local-cli.outputFormat`: expected CLI output format (`mp3`, `opus`, or `wav`; default `mp3` for audio attachments).
- `providers.tts-local-cli.timeoutMs`: command timeout in milliseconds (default `120000`).
- `providers.tts-local-cli.cwd`: optional command working directory.
- `providers.tts-local-cli.env`: optional string environment overrides for the command.
- `providers.inworld.baseUrl`: override Inworld API base URL (default `https://api.inworld.ai`).
- `providers.inworld.voiceId`: Inworld voice identifier (default `Sarah`).
- `providers.inworld.modelId`: Inworld TTS model (default `inworld-tts-1.5-max`; also supports `inworld-tts-1.5-mini`, `inworld-tts-1-max`, `inworld-tts-1`).
- `providers.inworld.temperature`: sampling temperature `0..2` (optional).
- `providers.google.model`: Gemini TTS model (default `gemini-3.1-flash-tts-preview`).
- `providers.google.voiceName`: Gemini prebuilt voice name (default `Kore`; `voice` is also accepted).
- `providers.google.audioProfile`: natural-language style prompt prepended before the spoken text.
- `providers.google.speakerName`: optional speaker label prepended before the spoken text when your TTS prompt uses a named speaker.
- `providers.google.baseUrl`: override the Gemini API base URL. Only `https://generativelanguage.googleapis.com` is accepted.
  - If `messages.tts.providers.google.apiKey` is omitted, TTS can reuse `models.providers.google.apiKey` before env fallback.
- `providers.gradium.baseUrl`: override Gradium API base URL (default `https://api.gradium.ai`).
- `providers.gradium.voiceId`: Gradium voice identifier (default Emma, `YTpq7expH9539ERJ`).
- `providers.volcengine.apiKey`: BytePlus Seed Speech API key (env:
  `VOLCENGINE_TTS_API_KEY` or `BYTEPLUS_SEED_SPEECH_API_KEY`).
- `providers.volcengine.resourceId`: BytePlus Seed Speech resource id (default
  `seed-tts-1.0`, env: `VOLCENGINE_TTS_RESOURCE_ID`; use `seed-tts-2.0` when
  your BytePlus project has TTS 2.0 entitlement).
- `providers.volcengine.appKey`: BytePlus Seed Speech app key header (default
  `aGjiRDfUWi`, env: `VOLCENGINE_TTS_APP_KEY`).
- `providers.volcengine.baseUrl`: override the Seed Speech TTS HTTP endpoint
  (env: `VOLCENGINE_TTS_BASE_URL`).
- `providers.volcengine.appId`: legacy Volcengine Speech Console application id (env: `VOLCENGINE_TTS_APPID`).
- `providers.volcengine.token`: legacy Volcengine Speech Console access token (env: `VOLCENGINE_TTS_TOKEN`).
- `providers.volcengine.cluster`: legacy Volcengine TTS cluster (default `volcano_tts`, env: `VOLCENGINE_TTS_CLUSTER`).
- `providers.volcengine.voice`: voice type (default `en_female_anna_mars_bigtts`, env: `VOLCENGINE_TTS_VOICE`).
- `providers.volcengine.speedRatio`: provider-native speed ratio.
- `providers.volcengine.emotion`: provider-native emotion tag.
- `providers.xai.apiKey`: xAI TTS API key (env: `XAI_API_KEY`).
- `providers.xai.baseUrl`: override the xAI TTS base URL (default `https://api.x.ai/v1`, env: `XAI_BASE_URL`).
- `providers.xai.voiceId`: xAI voice id (default `eve`; current live voices: `ara`, `eve`, `leo`, `rex`, `sal`, `una`).
- `providers.xai.language`: BCP-47 language code or `auto` (default `en`).
- `providers.xai.responseFormat`: `mp3`, `wav`, `pcm`, `mulaw`, or `alaw` (default `mp3`).
- `providers.xai.speed`: provider-native speed override.
- `providers.xiaomi.apiKey`: Xiaomi MiMo API key (env: `XIAOMI_API_KEY`).
- `providers.xiaomi.baseUrl`: override the Xiaomi MiMo API base URL (default `https://api.xiaomimimo.com/v1`, env: `XIAOMI_BASE_URL`).
- `providers.xiaomi.model`: TTS model (default `mimo-v2.5-tts`, env: `XIAOMI_TTS_MODEL`; `mimo-v2-tts` is also supported).
- `providers.xiaomi.voice`: MiMo voice id (default `mimo_default`, env: `XIAOMI_TTS_VOICE`).
- `providers.xiaomi.format`: `mp3` or `wav` (default `mp3`, env: `XIAOMI_TTS_FORMAT`).
- `providers.xiaomi.style`: optional natural-language style instruction sent as the user message; it is not spoken.
- `providers.openrouter.apiKey`: OpenRouter API key (env: `OPENROUTER_API_KEY`; can reuse `models.providers.openrouter.apiKey`).
- `providers.openrouter.baseUrl`: override the OpenRouter TTS base URL (default `https://openrouter.ai/api/v1`; legacy `https://openrouter.ai/v1` is normalized).
- `providers.openrouter.model`: OpenRouter TTS model id (default `hexgrad/kokoro-82m`; `modelId` is also accepted).
- `providers.openrouter.voice`: provider-specific voice id (default `af_alloy`; `voiceId` is also accepted).
- `providers.openrouter.responseFormat`: `mp3` or `pcm` (default `mp3`).
- `providers.openrouter.speed`: provider-native speed override.
- `providers.microsoft.enabled`: allow Microsoft speech usage (default `true`; no API key).
- `providers.microsoft.voice`: Microsoft neural voice name (e.g. `en-US-MichelleNeural`).
- `providers.microsoft.lang`: language code (e.g. `en-US`).
- `providers.microsoft.outputFormat`: Microsoft output format (e.g. `audio-24khz-48kbitrate-mono-mp3`).
  - See Microsoft Speech output formats for valid values; not all formats are supported by the bundled Edge-backed transport.
- `providers.microsoft.rate` / `providers.microsoft.pitch` / `providers.microsoft.volume`: percent strings (e.g. `+10%`, `-5%`).
- `providers.microsoft.saveSubtitles`: write JSON subtitles alongside the audio file.
- `providers.microsoft.proxy`: proxy URL for Microsoft speech requests.
- `providers.microsoft.timeoutMs`: request timeout override (ms).
- `edge.*`: legacy alias for the same Microsoft settings. Run
  `openclaw doctor --fix` to rewrite persisted config to `providers.microsoft`.

## Model-driven overrides (default on)

By default, the model **can** emit TTS directives for a single reply.
When `messages.tts.auto` is `tagged`, these directives are required to trigger audio.

When enabled, the model can emit `[[tts:...]]` directives to override the voice
for a single reply, plus an optional `[[tts:text]]...[[/tts:text]]` block to
provide expressive tags (laughter, singing cues, etc) that should only appear in
the audio.

`provider=...` directives are ignored unless `modelOverrides.allowProvider: true`.

Example reply payload:

```
Here you go.

[[tts:voiceId=pMsXgVXv3BLzUgSXRplE model=eleven_v3 speed=1.1]]
[[tts:text]](laughs) Read the song once more.[[/tts:text]]
```

Available directive keys (when enabled):

- `provider` (registered speech provider id, for example `openai`, `elevenlabs`, `google`, `gradium`, `minimax`, `microsoft`, `volcengine`, `vydra`, `xai`, or `xiaomi`; requires `allowProvider: true`)
- `voice` (OpenAI, Gradium, Volcengine, or Xiaomi voice), `voiceName` / `voice_name` / `google_voice` (Google voice), or `voiceId` (ElevenLabs / Gradium / MiniMax / xAI)
- `model` (OpenAI TTS model, ElevenLabs model id, MiniMax model, or Xiaomi MiMo TTS model) or `google_model` (Google TTS model)
- `stability`, `similarityBoost`, `style`, `speed`, `useSpeakerBoost`
- `vol` / `volume` (MiniMax volume, 0-10)
- `pitch` (MiniMax integer pitch, -12 to 12; fractional values are truncated before the MiniMax request)
- `emotion` (Volcengine emotion tag)
- `applyTextNormalization` (`auto|on|off`)
- `languageCode` (ISO 639-1)
- `seed`

Disable all model overrides:

```json5
{
  messages: {
    tts: {
      modelOverrides: {
        enabled: false,
      },
    },
  },
}
```

Optional allowlist (enable provider switching while keeping other knobs configurable):

```json5
{
  messages: {
    tts: {
      modelOverrides: {
        enabled: true,
        allowProvider: true,
        allowSeed: false,
      },
    },
  },
}
```

## Per-user preferences

Slash commands write local overrides to `prefsPath` (default:
`~/.openclaw/settings/tts.json`, override with `OPENCLAW_TTS_PREFS` or
`messages.tts.prefsPath`).

Stored fields:

- `enabled`
- `provider`
- `maxLength` (summary threshold; default 1500 chars)
- `summarize` (default `true`)

These override `messages.tts.*` for that host.

## Output formats (fixed)

- **Feishu / Matrix / Telegram / WhatsApp**: voice-note replies prefer Opus (`opus_48000_64` from ElevenLabs, `opus` from OpenAI).
  - 48kHz / 64kbps is a good voice message tradeoff.
- **Feishu**: when a voice-note reply is produced as MP3/WAV/M4A or another
  likely audio file, the Feishu plugin transcodes it to 48kHz Ogg/Opus with
  `ffmpeg` before sending the native `audio` bubble. If conversion fails, Feishu
  receives the original file as an attachment.
- **Other channels**: MP3 (`mp3_44100_128` from ElevenLabs, `mp3` from OpenAI).
  - 44.1kHz / 128kbps is the default balance for speech clarity.
- **MiniMax**: MP3 (`speech-2.8-hd` model, 32kHz sample rate) for normal audio attachments. For voice-note targets such as Feishu and Telegram, OpenClaw transcodes the MiniMax MP3 to 48kHz Opus with `ffmpeg` before delivery.
- **Xiaomi MiMo**: MP3 by default, or WAV when configured. For voice-note targets such as Feishu and Telegram, OpenClaw transcodes Xiaomi output to 48kHz Opus with `ffmpeg` before delivery.
- **Local CLI**: uses the configured `outputFormat`. Voice-note targets are
  converted to Ogg/Opus and telephony output is converted to raw 16 kHz mono PCM
  with `ffmpeg`.
- **Google Gemini**: Gemini API TTS returns raw 24kHz PCM. OpenClaw wraps it as WAV for audio attachments, transcodes it to 48kHz Opus for voice-note targets, and returns PCM directly for Talk/telephony.
- **Gradium**: WAV for audio attachments, Opus for voice-note targets, and `ulaw_8000` at 8 kHz for telephony.
- **Inworld**: MP3 for normal audio attachments, native `OGG_OPUS` for voice-note targets, and raw `PCM` at 22050 Hz for Talk/telephony.
- **xAI**: MP3 by default; `responseFormat` may be `mp3`, `wav`, `pcm`, `mulaw`, or `alaw`. OpenClaw uses xAI's batch REST TTS endpoint and returns a complete audio attachment; xAI's streaming TTS WebSocket is not used by this provider path. Native Opus voice-note format is not supported by this path.
- **Microsoft**: uses `microsoft.outputFormat` (default `audio-24khz-48kbitrate-mono-mp3`).
  - The bundled transport accepts an `outputFormat`, but not all formats are available from the service.
  - Output format values follow Microsoft Speech output formats (including Ogg/WebM Opus).
  - Telegram `sendVoice` accepts OGG/MP3/M4A; use OpenAI/ElevenLabs if you need
    guaranteed Opus voice messages.
  - If the configured Microsoft output format fails, OpenClaw retries with MP3.

OpenAI/ElevenLabs output formats are fixed per channel (see above).

## Auto-TTS behavior

When enabled, OpenClaw:

- skips TTS if the reply already contains media or a `MEDIA:` directive.
- skips very short replies (< 10 chars).
- summarizes long replies when enabled using `agents.defaults.model.primary` (or `summaryModel`).
- attaches the generated audio to the reply.

If the reply exceeds `maxLength` and summary is off (or no API key for the
summary model), audio
is skipped and the normal text reply is sent.

## Flow diagram

```
Reply -> TTS enabled?
  no  -> send text
  yes -> has media / MEDIA: / short?
          yes -> send text
          no  -> length > limit?
                   no  -> TTS -> attach audio
                   yes -> summary enabled?
                            no  -> send text
                            yes -> summarize (summaryModel or agents.defaults.model.primary)
                                      -> TTS -> attach audio
```

## Slash command usage

There is a single command: `/tts`.
See [Slash commands](/tools/slash-commands) for enablement details.

Discord note: `/tts` is a built-in Discord command, so OpenClaw registers
`/voice` as the native command there. Text `/tts ...` still works.

```
/tts off
/tts on
/tts status
/tts provider openai
/tts limit 2000
/tts summary off
/tts audio Hello from OpenClaw
```

Notes:

- Commands require an authorized sender (allowlist/owner rules still apply).
- `commands.text` or native command registration must be enabled.
- Config `messages.tts.auto` accepts `off|always|inbound|tagged`.
- `/tts on` writes the local TTS preference to `always`; `/tts off` writes it to `off`.
- Use config when you want `inbound` or `tagged` defaults.
- `limit` and `summary` are stored in local prefs, not the main config.
- `/tts audio` generates a one-off audio reply (does not toggle TTS on).
- `/tts status` includes fallback visibility for the latest attempt:
  - success fallback: `Fallback: <primary> -> <used>` plus `Attempts: ...`
  - failure: `Error: ...` plus `Attempts: ...`
  - detailed diagnostics: `Attempt details: provider:outcome(reasonCode) latency`
- OpenAI and ElevenLabs API failures now include parsed provider error detail and request id (when returned by the provider), which is surfaced in TTS errors/logs.

## Agent tool

The `tts` tool converts text to speech and returns an audio attachment for
reply delivery. When the channel is Feishu, Matrix, Telegram, or WhatsApp,
the audio is delivered as a voice message rather than a file attachment.
Feishu can transcode non-Opus TTS output on this path when `ffmpeg` is
available.
WhatsApp sends visible text separately from PTT voice-note audio because clients
do not consistently render captions on voice notes.
It accepts optional `channel` and `timeoutMs` fields; `timeoutMs` is a
per-call provider request timeout in milliseconds.

## Gateway RPC

Gateway methods:

- `tts.status`
- `tts.enable`
- `tts.disable`
- `tts.convert`
- `tts.setProvider`
- `tts.providers`

## Related

- [Media overview](/tools/media-overview)
- [Music generation](/tools/music-generation)
- [Video generation](/tools/video-generation)