> ## Documentation Index
> Fetch the complete documentation index at: https://docs.agentline.cloud/llms.txt
> Use this file to discover all available pages before exploring further.

# Update Agent

> Update an AI voice agent's configuration.

Modify any combination of the agent's settings: system prompt,
voice, greeting, transfer number, or voicemail message.
Changes take effect on the next call the agent handles.
Only include the fields you want to change — unset fields are preserved.



## OpenAPI

````yaml /openapi.json patch /v1/agents/{agent_id}
openapi: 3.1.0
info:
  title: AgentLine
  description: >-
    AgentLine gives every AI agent a real phone number, a human-like voice, and
    the ability to make and receive calls and SMS autonomously. This SDK covers
    the core developer surface: agents, numbers, calls, messages, events,
    webhooks, billing, and voice.
  version: 0.3.0
  summary: Phone numbers, voice, and SMS for AI agents.
  contact:
    name: AgentLine
    url: https://agentline.cloud
  license:
    name: MIT
    url: https://opensource.org/license/mit
servers:
  - url: https://api.agentline.cloud
    description: Production
security:
  - API Key or OAuth: []
paths:
  /v1/agents/{agent_id}:
    patch:
      tags:
        - Agents
      summary: Update Agent
      description: |-
        Update an AI voice agent's configuration.

        Modify any combination of the agent's settings: system prompt,
        voice, greeting, transfer number, or voicemail message.
        Changes take effect on the next call the agent handles.
        Only include the fields you want to change — unset fields are preserved.
      operationId: update_agent
      parameters:
        - name: agent_id
          in: path
          required: true
          schema:
            type: string
            title: Agent Id
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/AgentUpdate'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      security:
        - API Key or OAuth: []
components:
  schemas:
    AgentUpdate:
      properties:
        name:
          anyOf:
            - type: string
            - type: 'null'
          title: Name
          description: New display name for the AI voice agent
        system_prompt:
          anyOf:
            - type: string
            - type: 'null'
          title: System Prompt
          description: >-
            Updated default instructions for ALL future calls (does not affect
            calls already in progress)
        initial_greeting:
          anyOf:
            - type: string
            - type: 'null'
          title: Initial Greeting
          description: Updated default greeting for ALL future calls (inbound and outbound)
        voice_id:
          anyOf:
            - type: string
            - type: 'null'
          title: Voice Id
          description: New TTS voice preset name or Cartesia voice UUID
        transfer_number:
          anyOf:
            - type: string
            - type: 'null'
          title: Transfer Number
          description: Updated transfer phone number in E.164 format
        voicemail_message:
          anyOf:
            - type: string
            - type: 'null'
          title: Voicemail Message
          description: Updated voicemail message
        owner_phone:
          anyOf:
            - type: string
            - type: 'null'
          title: Owner Phone
          description: Updated owner phone number in E.164 format for task mode
      additionalProperties: false
      type: object
      title: AgentUpdate
    HTTPValidationError:
      properties:
        detail:
          items:
            $ref: '#/components/schemas/ValidationError'
          type: array
          title: Detail
      type: object
      title: HTTPValidationError
    ValidationError:
      properties:
        loc:
          items:
            anyOf:
              - type: string
              - type: integer
          type: array
          title: Location
        msg:
          type: string
          title: Message
        type:
          type: string
          title: Error Type
        input:
          title: Input
        ctx:
          type: object
          title: Context
      type: object
      required:
        - loc
        - msg
        - type
      title: ValidationError
  securitySchemes:
    API Key or OAuth:
      type: http
      description: >-
        AgentLine API key. Get one via the email OTP flow (POST /v1/auth/otp
        then POST /v1/auth/verify). Pass as: Authorization: Bearer sk_live_...
      scheme: bearer
      bearerFormat: API key (sk_live_...)
      x-fern-bearer:
        name: apiKey
        env: AGENTLINE_API_KEY

````