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Retell AI Create Retell Llm API

The Create Retell Llm API from Retell AI — 1 operation(s) for create retell llm.

Retell AI Create Retell Llm API is one of 78 APIs that Retell AI publishes on the APIs.io network, described by a machine-readable OpenAPI specification and an AsyncAPI event-driven specification.

Tagged areas include Create Retell Llm. The published artifact set on APIs.io includes an OpenAPI specification, API documentation, an AsyncAPI specification, and pricing.

This API exposes 1 operation across 1 path, and defines 44 schemas. It is described by OpenAPI 3.0.3, at version 3.0.0.

Requests are made against a single base URL, https://api.retellai.com.

1 operations 1 paths 44 schemas 1 POST

Metadata

The identity and technical contract details declared by the specification.

Specification
OpenAPI 3.0.3
API Version
3.0.0
Base URL
https://api.retellai.com
Authentication
HTTP Bearer
License
Resource Areas
1

Authentication & Security 1

Retell AI Create Retell Llm API declares 1 security scheme for authenticating requests. It accepts HTTP bearer tokens (string) (api_key). By default, every request must be authenticated.

  • api_key — Authentication header containing API key (find it in dashboard). The format is "Bearer YOURAPIKEY"

Paths & Operations 1

Across 1 path, the API surfaces 1 operation — 1 POST. Each is listed below with its method, path, parameters, and response codes.

Create Retell Llm 1
POST
/create-retell-llm
Create a new Retell LLM Response Engine that can be attached to an agent. This is used to generate response output for the agent.
createRetellLLM body → 201400401500

Schemas 44

The contract defines 44 schemas that model the data the API accepts and returns. The most detailed are CustomTool (16 properties), AgentSwapTool (12 properties), MCPTool (11 properties), CodeTool (11 properties). Each schema is shown below with its type and property counts.

State
object
4 properties 1 required
RetellLLMResponse
TransferDestinationPredefined
object
3 properties 2 required
ToolParameter
object
The parameters the functions accepts, described as a JSON Schema object. See [JSON Schema reference](https://json-schema.org/understanding-json-schema/) for do…
3 properties 2 required
Tool
TransferOptionColdTransfer
object
4 properties 1 required
TransferDestination
MCP
object
5 properties 2 required
WarmTransferStaticMessage
object
2 properties
AgentSwapWebhookSetting
string
TransferDestinationInferred
object
2 properties 2 required
CodeTool
object
11 properties 3 required
CheckAvailabilityCalTool
object
6 properties 4 required
SendSMSTool
object
7 properties 3 required
SmsContentInferred
object
2 properties
BookAppointmentCalTool
object
6 properties 4 required
TransferOptionWarmTransfer
object
10 properties 1 required
CancelTransferTool
object
6 properties 2 required
MCPTool
object
11 properties 3 required
ExtractDynamicVariableTool
object
4 properties 4 required
TransferCallTool
object
10 properties 4 required
SmsContent
TransferOptionAgenticWarmTransfer
object
7 properties 2 required
PressDigitTool
object
4 properties 2 required
KBConfig
object
2 properties
RetellLlmRequest
SmsContentTemplate
object
2 properties 2 required
CustomTool
object
16 properties 3 required
SmsContentPredefined
object
2 properties
TransferOption
AgentVersionReference
Agent version reference. Supports a numeric version (for example 3) or a tag/environment name (for example "prod"). When a tag is provided, resolution uses tha…
WarmTransferPrompt
object
2 properties
EndCallTool
object
6 properties 2 required
BooleanAnalysisData
object
5 properties 3 required
BridgeTransferTool
object
6 properties 2 required
StringAnalysisData
object
6 properties 3 required
AgentSwapTool
object
12 properties 4 required
RetellLlmOverride
object
Override properties for Retell LLM configuration in agent override requests.
10 properties
AnalysisData
NumberAnalysisData
object
5 properties 3 required
NullableLLMModel
string
Available LLM models for agents.
PostCallAnalysisSetting
string
StateEdge
object
3 properties 2 required
EnumAnalysisData
object
6 properties 4 required

Specification

The full machine-readable OpenAPI contract behind this narrative.

Source

retell-ai-create-retell-llm-api-openapi.yml Raw ↑

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