This endpoint allows you to update the configuration of an existing AI assistant. All fields are optional – only the fields provided will be updated. For detailed field descriptions and options, see Create Assistant.
Array of additional language IDs the assistant can speak. Replaces existing secondary languages. Pass an empty array [] to remove all secondary languages.
Array of custom mid-call tool IDs to synchronize. Replaces all existing tool assignments. Pass an empty array [] to remove all tools. Each tool must belong to your account.
Array of built-in tools. Replaces all existing built-in tools. Pass an empty array [] to remove all tools.
Show Tool Types
call_transfer - Transfer the call to another phone number
phone_number (required): Phone number to transfer to
description: When to transfer the call
custom: If true, AI can determine transfer number dynamically
timezone: Timezone for transfer availability
warm_transfer: Send a message to the customer before transferring (default: false)
warm_transfer_message: Prompt telling the AI what to say before transferring (e.g., “Tell the customer that the call is being transferred.”)
warm_call_transfer - Warm transfer with supervisor briefing
supervisor_phone (required): Phone number to dial for the warm transfer (e.g., “+14155552001”). If custom_sip is enabled, this is a SIP address or internal extension instead.
outbound_phone_id (required): ID of the phone number used to dial the supervisor. See Get Phone Numbers.
description (required): When to transfer — describes when the AI should initiate the warm transfer (e.g., “Transfer the call to a human supervisor when the customer requests to speak with a real person.”)
custom_sip: Enable to enter a custom SIP address or internal extension instead of a phone number (default: false)
caller_id_mode: What phone number the supervisor sees when receiving the call. Options: outbound_number (default — shows the outbound phone number), customer_number (shows the caller’s number), custom (shows a custom number)
custom_caller_id: Custom phone number shown to supervisor. Only used when caller_id_mode is custom.
hold_music: Audio played to the caller while on hold. Options: hold_music (default — plays default hold music), none (silence, no music)
hold_music_volume: Volume level for hold music, 0–100 (default: 80)
hold_message: Message spoken to caller before placing them on hold (default: “Please hold while I connect you with a supervisor.”)
summary_instructions: Instructions for how the AI should brief the supervisor about the call (default: “Introduce the conversation from your perspective:\n- WHO is calling (name, company if mentioned)\n- WHY they called (their goal or problem)\n- WHY a human is needed at this point\n\nKeep it brief (2-3 sentences).”)
briefing_initial_message: The first message the AI says to the supervisor when they answer (default: “Hello! I have a caller on the line who needs your assistance. May I brief you on the situation?”)
connected_message: Message spoken to caller after supervisor is connected (default: “You are now connected with a supervisor. I’ll leave you to it.”)
end_call - End the call programmatically
description: When the AI should end the call
dtmf_input - Send DTMF tones (keypad input)
description: When to use DTMF input (for IVR navigation)
collect_keypad - Collect keypad input from the caller
timeout: Seconds to wait for input, 1–30 (default: 5)
stop_key: Key that ends input. Options: # (default), *
calendar_integration - Schedule appointments via Cal.com
calcom_api_key (required): Your Cal.com API key
calcom_event_slug (required): The event type slug from Cal.com
calcom_team_slug: Team slug if the event belongs to a Cal.com team
calcom_endpoint: Cal.com API region. Options: us (default — https://api.cal.com), eu (https://api.cal.eu), custom (uses calcom_custom_endpoint)
calcom_custom_endpoint: Custom Cal.com API base URL. Only used when calcom_endpoint is custom (e.g., https://my-calcom-instance.com).
calcom_booking_fields: Array of custom booking fields for the event. Each field has: slug (required), type (required, e.g. “text”, “email”, “phone”, “select”), label (required), required (default: false), options (array of options for select fields)
description: When to offer scheduling
assistant_transfer - Hand off the conversation to a different AI assistant mid-call (swaps voice, LLM, and STT to the target assistant)
assistant_id (required): ID of the target assistant. Must belong to your account and cannot be the assistant being updated (no self-transfer).
description: When to transfer (max 500 chars, default: “Transfer the conversation to this assistant when appropriate.”)
message_before_transfer: Optional message the AI speaks before switching to the target assistant (max 500 chars).
speak_transfer_greeting: If true, the target assistant speaks its configured initial message after the transfer completes (default: true)
"tools": [ { "type": "dtmf_input", "description": "Navigate IVR when needed" }, { "type": "warm_call_transfer", "supervisor_phone": "+1234567890", "outbound_phone_id": 7, "description": "Transfer the call to a human supervisor when the customer requests to speak with a real person.", "custom_sip": false, "caller_id_mode": "outbound_number", "hold_music": "hold_music", "hold_music_volume": 80, "hold_message": "Please hold while I connect you with a supervisor.", "summary_instructions": "Introduce the conversation from your perspective:\n- WHO is calling (name, company if mentioned)\n- WHY they called (their goal or problem)\n- WHY a human is needed at this point\n\nKeep it brief (2-3 sentences).", "briefing_initial_message": "Hello! I have a caller on the line who needs your assistance. May I brief you on the situation?", "connected_message": "You are now connected with a supervisor. I'll leave you to it." }, { "type": "collect_keypad", "timeout": 5, "stop_key": "#" }, { "type": "assistant_transfer", "assistant_id": 14765, "description": "Transfer to the Support Assistant when the customer needs technical help.", "message_before_transfer": "Sure — let me transfer you to our support specialist.", "speak_transfer_greeting": true }, { "type": "end_call", "description": "End call when done" }]
When you list assistants, each configured tool is returned as { "type": "...", "data": { ... } } with the same field names nested under data (not top-level).
{ "reengagement_interval": 15, "reengagement_prompt": "Are you still there? I'm here to help.", "end_call_on_voicemail": true, "voice_mail_message": "Hello, please call us back at your earliest convenience."}
