Vocametrix Voice Analysis

@vocametrix/mcp-server

Official Model Context Protocol server for the Vocametrix voice analysis API.

Gives any MCP-compatible AI assistant (Claude Desktop, Cursor, Cline, etc.) direct access to clinical voice metrics, pronunciation assessment, speech transcription, and AI-powered therapy planning.

Quick start

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "vocametrix": {
      "command": "npx",
      "args": ["-y", "@vocametrix/mcp-server"],
      "env": {
        "VOCAMETRIX_API_KEY": "your-api-key-here"
      }
    }
  }
}

Get an API key at vocametrix.com/registration. MCP analysis uses purchased API credits; the website subscription and trial do not cover API calls.

Claude Code

Hosted server (no local install):

claude mcp add --transport http vocametrix https://mcp.vocametrix.com/mcp --header "x-api-key: your-api-key-here"

Or run it locally with npx:

claude mcp add vocametrix -e VOCAMETRIX_API_KEY=your-api-key-here -- npx -y @vocametrix/mcp-server

Add --scope user right after claude mcp add to make Vocametrix available in all your projects. Then type /mcp in Claude Code to check the connection.

ChatGPT (OAuth, API credits)

The optional /chatgpt/mcp endpoint links a user's API account through OAuth. The user approves access on the platform's consent page; ChatGPT receives revocable tokens, not the API key. Existing /mcp API-key clients and local stdio clients remain supported.

See ChatGPT setup and release checks for the matching platform changes, database migration, configuration, and tests. This integration must be deployed and tested in ChatGPT before public submission.

Tools

Voice quality (acoustic)

Tool	Description
vocametrix_calculate_avqi	Acoustic Voice Quality Index (AVQI) — overall dysphonia severity
vocametrix_calculate_dsi	Dysphonia Severity Index (DSI)
vocametrix_calculate_cpp	Cepstral Peak Prominence — breathiness, hoarseness
vocametrix_calculate_hnr	Harmonics-to-Noise Ratio (multi-band)
vocametrix_calculate_jitter_shimmer	Period and amplitude perturbation
vocametrix_calculate_voice_range_profile	Voice Range Profile
vocametrix_calculate_prosody_similarity	Prosody similarity between two utterances

Advanced voice analysis

Tool	Description
vocametrix_calculate_spectral	Spectral tilt, slope, and formant energy
vocametrix_calculate_formants	Formant frequencies F1–F4
vocametrix_calculate_sz_ratio	S/Z phonation ratio
vocametrix_calculate_gne	Glottal-to-Noise Excitation
vocametrix_calculate_h1_h2	H1–H2 harmonic difference
vocametrix_calculate_abi	Acoustic Breathiness Index
vocametrix_calculate_voice_dynamics	Dynamic range and fundamental frequency statistics

Ingestion utilities

Tool	Description
vocametrix_upload_audio	Upload a WAV file (base64) → returns a stable blobUrl
vocametrix_ingest_url	Ingest a public HTTPS WAV URL → returns a stable blobUrl

Speech and pronunciation

Tool	Description
vocametrix_assess_pronunciation	Phoneme-level pronunciation scoring
vocametrix_assess_pronunciation_with_pitch	Pronunciation + pitch analysis combined
vocametrix_transcribe_audio	Streaming ASR transcription with progress
vocametrix_synthesize_speech	Text-to-speech synthesis

Audio measures

Tool	Description
vocametrix_measure_sound_level	dB SPL and intensity statistics
vocametrix_extract_egemaps	Extended Geneva Minimalistic Acoustic Parameter Set (88 features)
vocametrix_detect_phonemes	French phoneme detection with confidence scores and timestamps
vocametrix_classify_stuttering	Dysfluency classification

AI agents

Tool	Description
vocametrix_interpret_voice_metrics	Clinical interpretation of voice metrics
vocametrix_generate_exercises	Personalized voice/speech exercise generation
vocametrix_generate_word_list	Target word list generation for therapy
vocametrix_chat_speech_therapist	Conversational AI speech-language therapist
vocametrix_convert_french_to_ipa	French text → IPA phonetic transcription
vocametrix_interpret_spelling_attempt	Spelling correction agent
vocametrix_check_syntax	Syntax checking agent
vocametrix_vocabulary_tutor	Vocabulary tutoring agent
vocametrix_adapt_exercise	Adaptive exercise generation

Therapy planning

Not published on the ChatGPT endpoint (/chatgpt/mcp): these tools take a patient identifier and clinical history, which the ChatGPT app guidelines treat as protected health information. They remain available over stdio and /mcp.

Tool	Description
vocametrix_generate_therapy_plan	Generate an AI therapy plan
vocametrix_get_therapy_status	Poll therapy plan generation status
vocametrix_get_therapy_result	Fetch completed therapy plan
vocametrix_approve_therapy_plan	Approve a therapy plan

Workflow tools

Tool	Description
vocametrix_full_voice_assessment	Parallel AVQI + CPP + HNR + jitter/shimmer + spectral
vocametrix_batch_pronunciation	Assess a folder of WAV files. Reads the server's own filesystem, so it is only registered in stdio/local mode (VOCAMETRIX_MCP_LOCAL_FS=1) — not available on the hosted server
vocametrix_full_therapy_workflow	Generate → poll → fetch → approval flow

Resources

• vocametrix://docs/api — API quick reference (auth, rate limits, audio requirements, error codes)
• vocametrix://recording-guide — Recording protocols for every tool (sustained vowel, connected speech with language-specific reference sentences, glissando, sustained /s/ and /z/)
• vocametrix://thresholds/{metric} — Clinical reference thresholds for avqi, dsi, cpp, hnr, jitter-shimmer, gne

Prompts

• interpret_voice_assessment — Generate a clinical SLP-style interpretation report from assessment JSON
• compare_pre_post_therapy — Quantified pre/post therapy narrative with metric-by-metric comparison
• generate_session_report — SOAP-format progress note from pronunciation assessment data

Audio requirements

• Format: WAV (16-bit PCM recommended)
• Sustained vowel tasks: 3+ seconds of /a/ phonation
• Connected speech tasks: 5–30 seconds of read passage
• Minimum sampling rate: 16 kHz

How to pass audio to a tool

The audioPath parameter accepts several input types, but which ones are valid depends on how the MCP server is running:

Input	Hosted / remote server	Stdio / local server (npx, Claude Desktop)
https://... blobUrl from vocametrix_upload_audio	✅ recommended	✅
Public https://... URL to a WAV file	✅	✅
Public URL via vocametrix_ingest_url → returned blobUrl	✅ recommended for URL inputs	✅
data:audio/wav;base64,... data URL	✅	✅
Raw base64 string (≥ 512 chars)	✅	✅
Absolute local path (/home/..., C:\...)	❌ rejected	⚠️ requires VOCAMETRIX_MCP_LOCAL_FS=1

For chat clients that attach audio in the conversation (Claude.ai web/mobile, etc.), the LLM cannot pass an absolute path to a hosted server — it must call vocametrix_upload_audio first with the file content base64-encoded, then pass the returned blobUrl as audioPath to any analysis tool. The MCP descriptions guide the LLM toward this workflow automatically.

For stdio/local deployments where the MCP runs on the user's own machine, set VOCAMETRIX_MCP_LOCAL_FS=1 to allow analysis tools to read absolute local paths directly — convenient for batch processing of files already on disk.

Environment variables

Variable	Required	Description
VOCAMETRIX_API_KEY	Yes	Your Vocametrix API key
VOCAMETRIX_MCP_LOCAL_FS	No	Set to 1 to allow analysis tools to read absolute local file paths (stdio/local deployments only). Default off — local paths are rejected with an actionable error so chat clients are pushed toward the vocametrix_upload_audio → blobUrl workflow.
VOCAMETRIX_MCP_ALLOW_PRIVATE_HOSTS	No	Set to 1 to allow fetching audio URLs whose host resolves to a private, loopback or link-local address (a LAN file server, for instance). Default off, including in stdio/local mode: the caller of an MCP tool is an LLM, and an LLM that has read a hostile page can be talked into pointing these tools at your own network.

Development

git clone https://github.com/Vocametrix/vocametrix-mcp.git
cd vocametrix-mcp
npm install
npm run build
npm test            # run unit tests
npm run inspector   # test with MCP Inspector

MCP Registry

Listed in the official MCP Registry under io.github.pmarmaroli/vocametrix-mcp. Available for one-click installation in MCP-compatible clients (Claude Desktop, Cursor, Zed, Windsurf, and more).

Related projects

The Vocametrix ecosystem:

• 📘 Vocametrix API documentation — full reference for the underlying REST API powering this MCP server.
• 📐 OpenAPI 3.1 specification — machine-readable schema for all 49 endpoints.
• 🐍 vocametrix-python — official Python SDK if you want direct API access from Python (pip install vocametrix).
• 🟦 vocametrix-js — official TypeScript / JavaScript SDK used internally by this MCP server (npm install vocametrix).

License

MIT — see LICENSE