SLNG Voice Agents API

Schemas

ModelsConfig

stt

string · required

STT model (provider/model:variant)

llm

string · required

LLM model (provider/model)

tts

string · required

TTS model (provider/model:variant)

tts_voice

string · required

Voice identifier for TTS

object

Additional STT model parameters

object

Additional LLM model parameters (e.g., temperature)

object

Additional TTS model parameters

TemplateTool

type

string · enum · required

Tool type

Enum values:

template

template

string · enum · required

Built-in template name

Enum values:

hangup

voicemail_detection

prompt

string

Override default tool prompt

WebhookToolAuthBearer

type

string · enum · required

Enum values:

bearer

token

string · required

Bearer token

WebhookToolAuthHmac

type

string · enum · required

Enum values:

hmac

secret

string · required

HMAC secret

WebhookTool

type

string · enum · required

Tool type

Enum values:

webhook

name

string · maxLength: 64 · pattern: ^[a-z_][a-z0-9_]*$ · required

Tool name (lowercase, underscores allowed)

description

string · maxLength: 500 · required

Tool description for the LLM

url

string · uri · required

Webhook endpoint URL

parameters

object · required

JSON Schema for tool parameters

Authentication configuration

timeout_seconds

number · min: 1 · max: 60

Webhook timeout in seconds

Default: 10

wait_for_response

boolean

Whether to wait for webhook response

Default: true

Tool

oneOf

Exactly one variant must match.

Decision Table

Variant	Matching Criteria
	type = object · type="template" · requires: template
	type = object · type="webhook" · requires: name, description, url +1 more

Properties for Variant 1:

type

string · enum · required

Tool type

Enum values:

template

template

string · enum · required

Built-in template name

Enum values:

hangup

voicemail_detection

prompt

string

Override default tool prompt

ToolOut

type

string · enum

Tool type

Enum values:

template

webhook

template

string

Template name (for template tools)

prompt

string

Custom prompt

name

string

Tool name (for webhook tools)

description

string

Tool description

url

string

Webhook URL

parameters

object

JSON Schema for parameters

auth_type

string

Auth type (bearer/hmac) - secrets redacted

timeout_seconds

number

wait_for_response

boolean

CreateAgentRequest

name

string · maxLength: 255 · required

Agent name (must be unique within organisation)

system_prompt

string · required

System prompt for the agent (supports Handlebars templates with {{variable}} syntax)

greeting

string · required

Initial greeting message spoken by the agent

language

string · maxLength: 10 · required

Language code

object · required

slng_api_key

string · required

SLNG API key for the agent to use when making API calls

livekit_deployment

string · required

LiveKit deployment name

enable_interruptions

boolean

Whether the agent can be interrupted while speaking

Default: true

array

Tools available to the agent

object

Default values for template variables in system_prompt

UpdateAgentRequest

name

string · maxLength: 255

Agent name (must be unique within organisation)

system_prompt

string

System prompt for the agent (supports Handlebars templates)

greeting

string

Initial greeting message

language

string · maxLength: 10

Language code

object

enable_interruptions

boolean

Whether the agent can be interrupted while speaking

array

Tools available to the agent

slng_api_key

string

SLNG API key for the agent

livekit_deployment

string

LiveKit deployment name

object

Default values for template variables

AgentResponse

id

string · uuid

Agent UUID

organisation_id

string · uuid

Organisation UUID

name

string

Agent name

system_prompt

string

System prompt

greeting

string

Initial greeting message

language

string

Language code

object

enable_interruptions

boolean

Whether the agent can be interrupted

object[]

Tools with secrets redacted

livekit_deployment

string

LiveKit deployment name

object

Template variables extracted from system_prompt with their metadata

created_at

string · date-time

Creation timestamp

updated_at

string · date-time

Last update timestamp

deleted_at

string · date-time

Deletion timestamp (null if not deleted)

DispatchCallRequest

phone_number

string · pattern: ^\+[1-9]\d{1,14}$ · required

Phone number in E.164 format

object

Values for template variables in the system_prompt

DispatchCallResponse

call_id

string · uuid

Call UUID

message

string

Status message

ErrorResponse

error

string

Error message

detail

string

Additional error details

SubmitTranscriptRequest

object · required

Raw LiveKit session report including events, chat history, and metrics

SubmitTranscriptResponse

call_id

string · uuid

Call UUID

message

string

Status message

CallResponse

id

string · uuid

Call UUID

agent_id

string · uuid

Agent UUID

phone_number

string

Phone number in E.164 format

object

Template arguments provided for the call

rendered_prompt

string

The system prompt with template variables rendered

livekit_room_name

string

LiveKit room name for the call

livekit_dispatch_id

string

LiveKit dispatch ID

livekit_response

object

Raw response from LiveKit dispatch

livekit_session_report

object

Session report/transcript submitted after call completion

status

string

Call status (e.g., pending, dispatched, completed, failed)

error_message

string

Error message if call failed

created_at

string · date-time

When the call was created

updated_at

string · date-time

When the call was last updated

ModelsConfig

stt

string · required

STT model (provider/model:variant)

llm

string · required

LLM model (provider/model)

tts

string · required

TTS model (provider/model:variant)

tts_voice

string · required

Voice identifier for TTS

object

Additional STT model parameters

object

Additional LLM model parameters (e.g., temperature)

object

Additional TTS model parameters

WebhookTool

type

string · enum · required

Tool type

Enum values:

webhook

name

string · maxLength: 64 · pattern: ^[a-z_][a-z0-9_]*$ · required

Tool name (lowercase, underscores allowed)

description

string · maxLength: 500 · required

Tool description for the LLM

url

string · uri · required

Webhook endpoint URL

parameters

object · required

JSON Schema for tool parameters

Authentication configuration

timeout_seconds

number · min: 1 · max: 60

Webhook timeout in seconds

Default: 10

wait_for_response

boolean

Whether to wait for webhook response

Default: true

Tool

oneOf

Exactly one variant must match.

Decision Table

Variant	Matching Criteria
	type = object · type="template" · requires: template
	type = object · type="webhook" · requires: name, description, url +1 more

Properties for Variant 1:

type

string · enum · required

Tool type

Enum values:

template

template

string · enum · required

Built-in template name

Enum values:

hangup

voicemail_detection

prompt

string

Override default tool prompt

ToolOut

type

string · enum

Tool type

Enum values:

template

webhook

template

string

Template name (for template tools)

prompt

string

Custom prompt

name

string

Tool name (for webhook tools)

description

string

Tool description

url

string

Webhook URL

parameters

object

JSON Schema for parameters

auth_type

string

Auth type (bearer/hmac) - secrets redacted

timeout_seconds

number

wait_for_response

boolean

CreateAgentRequest

name

string · maxLength: 255 · required

Agent name (must be unique within organisation)

system_prompt

string · required

System prompt for the agent (supports Handlebars templates with {{variable}} syntax)

greeting

string · required

Initial greeting message spoken by the agent

language

string · maxLength: 10 · required

Language code

object · required

slng_api_key

string · required

SLNG API key for the agent to use when making API calls

livekit_deployment

string · required

LiveKit deployment name

enable_interruptions

boolean

Whether the agent can be interrupted while speaking

Default: true

array

Tools available to the agent

object

Default values for template variables in system_prompt

UpdateAgentRequest

name

string · maxLength: 255

Agent name (must be unique within organisation)

system_prompt

string

System prompt for the agent (supports Handlebars templates)

greeting

string

Initial greeting message

language

string · maxLength: 10

Language code

object

enable_interruptions

boolean

Whether the agent can be interrupted while speaking

array

Tools available to the agent

slng_api_key

string

SLNG API key for the agent

livekit_deployment

string

LiveKit deployment name

object

Default values for template variables

AgentResponse

id

string · uuid

Agent UUID

organisation_id

string · uuid

Organisation UUID

name

string

Agent name

system_prompt

string

System prompt

greeting

string

Initial greeting message

language

string

Language code

object

enable_interruptions

boolean

Whether the agent can be interrupted

object[]

Tools with secrets redacted

livekit_deployment

string

LiveKit deployment name

object

Template variables extracted from system_prompt with their metadata

created_at

string · date-time

Creation timestamp

updated_at

string · date-time

Last update timestamp

deleted_at

string · date-time

Deletion timestamp (null if not deleted)

CallResponse

id

string · uuid

Call UUID

agent_id

string · uuid

Agent UUID

phone_number

string

Phone number in E.164 format

object

Template arguments provided for the call

rendered_prompt

string

The system prompt with template variables rendered

livekit_room_name

string

LiveKit room name for the call

livekit_dispatch_id

string

LiveKit dispatch ID

livekit_response

object

Raw response from LiveKit dispatch

livekit_session_report

object

Session report/transcript submitted after call completion

status

string

Call status (e.g., pending, dispatched, completed, failed)

error_message

string

Error message if call failed

created_at

string · date-time

When the call was created

updated_at

string · date-time

When the call was last updated