Tool/Function Call

Webhook

POST

tool-calls

Webhooks

Last modified:2026-01-30 13:43:45

Maintainer:Jesper Rietbergen

Called when the AI needs to execute a tool/function during the conversation.

Sync tools: Must respond within 10 seconds with the result.
Async tools: Respond immediately with 200 OK (fire-and-forget).

Tools are defined in llm_config.tools[] with optional per-tool URL override.

Assistant Object

The payload includes the full assistant object containing:

All resolved configuration (after any overrides from assistant-request)

Any custom metadata you passed in the assistant-request response

Response Formats

Multiple response formats are supported:

Object format (recommended):

{"results": [{"tool_call_id": "tool_abc123", "result": {"name": "Jan"}}]}

Simple format:

{"result": {"name": "Jan"}}

Direct format (your data directly):

{"name": "Jan"}

Error format:

{"error": "Contact not found"}

Request

Authorization

Provide your bearer token in the

Authorization

header when making requests to protected resources.

Example:

Authorization: Bearer ********************

Body Params application/jsonRequired

Examples

Responses

🟢200

application/json

Tool result (for sync tools)

Body

Request Example

Shell

JavaScript

Java

Swift

curl --location --request POST 'https://your-api-server.com' \
--header 'Authorization: Bearer <token>' \
--header 'Content-Type: application/json' \
--data-raw '{
    "message": {
        "type": "tool-calls",
        "timestamp": "2025-12-13T12:00:00.000Z",
        "call": {
            "id": "5c4d030f-43e3-4e65-899e-8148521e660f",
            "type": "inbound_phone_call",
            "status": "in-progress"
        },
        "phone_number": {
            "number": "+31850835037",
            "name": "HMS Sovereign Demo"
        },
        "customer": {
            "number": "+31612345678"
        },
        "assistant": {
            "llm_config": {
                "provider": "openai",
                "model": "gpt-4.1"
            },
            "stt_config": {
                "provider": "deepgram",
                "model": "nova-3",
                "language": "nl"
            },
            "tts_config": {
                "provider": "elevenlabs",
                "voice_id": "ukiwGs47sHyibruHJ1vg"
            },
            "first_message": "Hello, how can I help you?",
            "autonomous_silence_handling": false,
            "voicemail_detection": false,
            "metadata": {
                "crm_id": "12345",
                "campaign_id": "summer-2025",
                "customer_tier": "premium"
            }
        },
        "tool_call_list": [
            {
                "id": "tool_abc123def456",
                "type": "function",
                "function": {
                    "name": "lookup_contact",
                    "arguments": {
                        "query": "John Smith"
                    }
                }
            }
        ]
    }
}'

Response Example

Object format (recommended)

{
    "results": [
        {
            "tool_call_id": "tool_abc123def456",
            "result": {
                "name": "John Smith",
                "email": "john@example.com",
                "phone": "+31612345678"
            }
        }
    ]
}

Modified at 2026-01-30 13:43:45

Dynamic assistant configuration webhook

Call Status Update

Tool/Function Call

Assistant Object#

Response Formats#

Request

Responses

Assistant Object

Response Formats