> ## Documentation Index > Fetch the complete documentation index at: https://docs.komaa.com/llms.txt > Use this file to discover all available pages before exploring further. # Configuration > Environment variables for openai-msteams-bridge: model, voice, instructions, secret, governor, vision, and MCP servers. The bridge is configured entirely by **environment variables** (a `.env` file works with `node --env-file=.env`). Numeric variables fail loudly at startup if set to a non-number, so a typo stops the process with a clear message rather than silently misbehaving - the same goes for a bad `OPENAI_VAD` value or malformed `OPENAI_MCP_SERVERS` JSON. ## Required | Variable | Meaning | | ---------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- | | `OPENAI_API_KEY` | Server-side OpenAI key with Realtime access. Never sent to the Teams side; opens the per-call Realtime session and synthesizes the goodbye. | | `WORKER_SHARED_SECRET` | Must equal the shared secret from StandIn pairing. Both sides sign the WebSocket upgrade with it; a mismatch is rejected with `401`. | ## The agent There is no dashboard - these variables define the agent: | Variable | Default | Meaning | | ----------------------- | ------------------ | ---------------------------------------------------------------------------------------------------------------------- | | `OPENAI_REALTIME_MODEL` | `gpt-realtime` | The Realtime model each per-call session runs. | | `OPENAI_VOICE` | model default | Output voice (e.g. `marin`, `cedar`, `alloy`). | | `OPENAI_INSTRUCTIONS` | a built-in default | Base system instructions. The bridge appends per-call caller context (name, tenant, direction) automatically. | | `OPENAI_FIRST_MESSAGE` | (unset) | Deterministic opening line the agent speaks as its first response - also the natural place for a spoken AI disclosure. | | `OPENAI_VAD` | `server_vad` | Turn detection: `server_vad` (volume-based) or `semantic_vad` (the model decides when the caller's turn is over). | ## Common options | Variable | Default | Meaning | | ------------------ | -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `PORT` | `8080` | Port the media WebSocket listens on. | | `BIND` | `0.0.0.0` | Bind address. | | `MAX_CALL_MINUTES` | `0` (off) | Bridge-side hard cap per call. On expiry the agent speaks a goodbye, then the call ends. **Keep it below 60**: the Realtime API caps sessions at 60 minutes server-side, and a call reaching that ceiling drops abruptly instead of saying goodbye. | | `OPENAI_TTS_VOICE` | (unset) | With a voice set, the time-limit goodbye is spoken as the **exact** `GOODBYE_TEXT` via the standalone TTS endpoint. Without it, the agent is asked to say goodbye (wording may vary). | | `GOODBYE_TEXT` | a default line | The goodbye the governor speaks. | ## Vision (the `look` tool) The `look` tool is registered automatically - nothing to define on the OpenAI side. The bridge answers it two ways: | Variable | Meaning | | ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | `VISION_API_URL` | Any OpenAI-compatible chat-completions endpoint with image input. When set, the bridge describes the frame and returns the text (the raw frame never leaves the bridge). | | `VISION_API_KEY` | Bearer key for that endpoint (optional for local models). | | `VISION_MODEL` | Model name for the vision endpoint. | Without a vision endpoint, `look` falls back to attaching the frame to the Realtime conversation as native image input (`gpt-realtime` is multimodal), which is only allowed when Teams recording is active. For a fully custom vision hook in code, see the [library API](https://komaa-com.github.io/openai-msteams-bridge/library-api/). ## Custom tools and MCP servers | Variable | Meaning | | -------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `OPENAI_MCP_SERVERS` | JSON array of remote MCP tool entries (`{"server_label", "server_url", "allowed_tools"?, "authorization"?}`) the **Realtime API executes server-side** - the bridge does nothing at call time. `server_url` must be https. `require_approval` defaults to `"never"` (a voice call has no approval UI), so scope servers with `allowed_tools`. | Function tools your own code executes (`lookup_order`, `transfer_call`, ...) are registered programmatically - see [Extending the agent's tools](https://komaa-com.github.io/openai-msteams-bridge/extending-tools/) and the [example](/openai/example#the-custom-tool). ## Advanced `OPENAI_TRANSCRIPTION_MODEL` (unset; needed for user-side transcript logging), `OPENAI_TTS_MODEL` (`gpt-4o-mini-tts`), `OPENAI_HOST` (`api.openai.com`, restricted to `*.openai.com` so the key cannot be exfiltrated elsewhere), `HMAC_FRESHNESS_MS` (default 60000), `MAX_CONNECTIONS` (64), `MAX_CONNECTIONS_PER_IP` (= total cap), `PRE_START_TIMEOUT_MS` (10000), `WORKER_IDLE_TIMEOUT_MS` (90000), `TLS_CERT_PATH` / `TLS_KEY_PATH` (native `wss://`), `LOG_LEVEL` (`info`), and `LOG_TRANSCRIPTS` (`false`; still gated on Teams recording being active). Full reference: [configuration-reference](https://komaa-com.github.io/openai-msteams-bridge/configuration-reference/). ## Privacy Caller audio, transcripts, any vision content, and MCP tool traffic transit OpenAI's cloud and are retained per your organization's OpenAI data controls. Keep `LOG_TRANSCRIPTS` off and vision unconfigured if not needed, and disclose the AI on the call via `OPENAI_FIRST_MESSAGE`. See [Governors and privacy](https://komaa-com.github.io/openai-msteams-bridge/governors-and-privacy/). ## Links