tts-mcp

Profile-driven MCP server for Google Cloud Text-to-Speech: define one profile per app/client so each tool always speaks with the right voice and settings.

Exposes three tools to any MCP client:

• tts_speak — synthesize text to audio and auto-play it
• tts_doctor — run diagnostics on auth, profile, and playback
• tts_stop — stop any currently playing audio

Voice, language, model, and format are locked per profile — the LLM can only control text content, speaking rate, and pitch.

Install

pip install tts-mcp

Or with uvx (no install needed):

uvx tts-mcp --help

Prerequisites

• Python 3.11+
• A Google Cloud project with the Cloud Text-to-Speech API enabled
• Google offers a generous free tier — up to 4 million characters/month (roughly 84 hours of English speech at a normal pace) for Standard and WaveNet voices, and 1 million characters/month (roughly 21 hours) for Neural2, Polyglot, Chirp 3: HD, and Studio voices, more than enough for most individual use. See TTS pricing for details.
• Google Cloud CLI (gcloud) for authentication
• macOS uses afplay for playback by default (configurable via profile)

Setup

1. Authenticate with Google Cloud

gcloud auth application-default login
gcloud auth application-default set-quota-project YOUR_PROJECT_ID

This stores credentials at ~/.config/gcloud/application_default_credentials.json, which the TTS client discovers automatically. No environment variables needed.

2. Create a profiles file

tts-mcp --init
${EDITOR:-vi} ~/.config/tts-mcp/profiles.json

This creates a starter config at ~/.config/tts-mcp/profiles.json with example profiles for every Google TTS voice tier. Edit it to pick your voice, format, and playback settings.

The server finds the profiles file automatically — no --profiles flag needed for the common case. The search order is:

1. --profiles flag or TTS_MCP_PROFILES_PATH env var (explicit override)
2. ~/.config/tts-mcp/profiles.json (XDG standard — created by tts-mcp --init)

MCP client setup

After running tts-mcp --init, no --profiles flag is needed — the server finds ~/.config/tts-mcp/profiles.json automatically. Just pass --profile to select which profile each client uses.

Claude Code

claude mcp add --transport stdio --scope user \
  speech -- tts-mcp --profile claude

OpenCode

Edit ~/.config/opencode/opencode.jsonc:

{
  "mcp": {
    "speech": {
      "type": "local",
      "command": ["tts-mcp", "--profile", "opencode"],
      "enabled": true,
      "timeout": 120000
    }
  }
}

Codex CLI

Edit ~/.codex/config.toml:

[mcp_servers.speech]
command = "tts-mcp"
args = ["--profile", "codex"]

Using uvx (no global install)

Any client config can use uvx instead of installing globally:

{
  "command": "uvx",
  "args": ["--update", "tts-mcp", "--profile", "opencode"]
}

Usage

In any MCP-enabled client, prompt naturally:

• Summarize this and read it aloud.
• Stop talking.

Tool names may appear prefixed by the client (e.g. speech_tts_speak, speech_tts_stop).

CLI reference

The package installs four commands. Each supports --help for full details. For normal usage, you only need tts-mcp --init plus your MCP client setup above; the commands below are mostly for diagnostics or manual testing.

tts-mcp — MCP server and management

tts-mcp --init              # create starter config at ~/.config/tts-mcp/profiles.json
tts-mcp --init --force      # overwrite existing config
tts-mcp --doctor            # diagnostics: auth, profile, voice, player
tts-mcp --profile casual    # start MCP server with a specific profile

Defaults:

• --profiles: TTS_MCP_PROFILES_PATH env var or "" (then auto-discovery runs)
• --profile: TTS_MCP_PROFILE_NAME env var or "" (then default_profile is used)
• --doctor, --init, --force: false

tts-speak — synthesize text to audio

tts-speak --text "Hello world" --voice en-US-Chirp3-HD-Fenrir --format wav --out hello.wav
tts-speak --text-file notes.txt --voice en-US-Neural2-D --format mp3 --out notes.mp3
tts-speak --ssml --text "<speak>Hello <break time='500ms'/> world</speak>" --out ssml.wav
echo "Piped text" | tts-speak --voice en-US-Casual-K --out piped.ogg

Options: --text, --text-file, --voice, --language, --model, --format (mp3/ogg/wav), --speaking-rate, --pitch, --out, --usage-log.

Defaults:

• --voice: ""
• --language: en-US
• --model: ""
• --format: mp3
• --speaking-rate: 1.0
• --pitch: 0.0
• --out: "" (auto-generates YYYYMMDD-HHMMSS-ms.ext in the current directory, local timezone)
• --usage-log: usage_log.csv
• input: if neither --text nor --text-file is provided, the CLI reads piped stdin or prompts for text

tts-voices — list available voices

tts-voices                              # list en-US voices (default language)
tts-voices --language en-US             # filter by language
tts-voices --language en-US --family Chirp3   # filter by family
tts-voices --limit 5                    # limit results

Defaults:

• --language: en-US
• --family: "" (no family filter)
• --limit: 0 (no limit)

tts-batch — generate samples for multiple voices

tts-batch --text-file test.txt --out-dir ./samples
tts-batch --text-file test.txt --families Chirp3,Neural2 --language en-US --format wav
tts-batch --text-file test.txt --limit 3   # first 3 matching voices only

Defaults:

• --families: "" (no family filter)
• --language: en-US
• --format: mp3
• --out-dir: ./out
• --speaking-rate: 1.0
• --pitch: 0.0
• --limit: 0 (all matching voices)
• --text-file: required

Profile system

Profiles are defined in a JSON file (see profiles.example.json):

{
  "default_profile": "opencode",
  "profiles": {
    "opencode": {
      "voice": "en-US-Chirp3-HD-Fenrir",
      "language": "en-US",
      "model": "models/chirp3-hd",
      "format": "wav",
      "speaking_rate": 1.0,
      "pitch": 0.0,
      "output_dir": "~/.local/share/tts-mcp/out",
      "usage_log": "~/.local/share/tts-mcp/usage_log.csv",
      "autoplay": true,
      "player_command": ["afplay", "{file}"]
    }
  }
}

Each profile locks: voice, language, model, format, output_dir, usage_log, autoplay, and player_command. Only speaking_rate and pitch can be overridden per tool call.

Troubleshooting

• Auth errors — run gcloud auth application-default login, or confirm GOOGLE_APPLICATION_CREDENTIALS is set.
• No audio — verify the player binary (e.g. afplay) exists, or change player_command in your profile.
• Tool timeout — playback is non-blocking, but if timeouts persist, increase the client's tool_timeout.
• Run diagnostics — tts-mcp --doctor checks auth, profile, voice, and player.

Development

git clone git@github.com:that-lucas/tts-mcp.git
cd tts-mcp
make setup    # creates venv, installs package + dev deps, sets git hooks
make test     # run pytest
make lint     # run ruff check + format check

See CONTRIBUTING.md for details.

License

MIT