> ## Documentation Index > Fetch the complete documentation index at: https://docs.voice.wixzel.com/llms.txt > Use this file to discover all available pages before exploring further. # Update an agent > Only the fields you send are changed. ## OpenAPI ````yaml /openapi.json patch /v1/agents/{id} openapi: 3.1.0 info: title: Wixzel Voice API version: '2026-09-01' description: >- APIs for AI voice agents. One key, one balance, every voice engine. ## Authentication Send your key as `Authorization: Bearer wv_live_...`. Keys are scoped — grant only what an integration needs. There is no admin scope. ## Versioning The `/v1` prefix covers additive changes. Behavioural changes ship behind a dated `Wixzel-Version` header, and existing keys keep the behaviour they were created with. ## Money Amounts are integer **micro-USD** (1,000,000 = $1.00). Voice usage is billed per second, per token and per character, so a float dollar figure cannot represent it without disagreeing with the ledger. ## Errors Every error carries a stable `code` and a `request_id`. Match on `code`; the `message` is for humans and may change. contact: name: Wixzel Voice url: https://voice.wixzel.com servers: - url: https://api.voice.wixzel.com description: Production security: [] tags: - name: Calls description: Place calls and read what happened on them. - name: Agents description: The prompt, voice and behaviour of a caller. - name: Leads description: People to call, and data to merge into prompts. - name: Campaigns description: Call a list of leads with one agent. - name: Knowledge bases description: Facts an agent can draw on mid-call. - name: Phone numbers description: Numbers on your SIP trunks. - name: SIP trunks description: Your carrier connections. - name: Appointments description: Bookings, including ones agents make on calls. - name: Usage description: Itemised billing lines. - name: Billing description: Balance, ledger and top-ups. - name: API keys description: Create, scope and rotate keys. - name: Engines description: What the platform can serve, and what it costs. paths: /v1/agents/{id}: patch: tags: - Agents summary: Update an agent description: Only the fields you send are changed. parameters: - schema: type: string pattern: ^[0-9a-f]{24}$ example: 6a96a3ead6e886d42462dd3e required: true name: id in: path requestBody: content: application/json: schema: $ref: '#/components/schemas/UpdateAgent' responses: '200': description: The updated an agent content: application/json: schema: $ref: '#/components/schemas/Agent' '400': description: Invalid request content: application/json: schema: $ref: '#/components/schemas/Error' '401': description: Missing or invalid API key content: application/json: schema: $ref: '#/components/schemas/Error' '403': description: Key lacks the required scope content: application/json: schema: $ref: '#/components/schemas/Error' '404': description: No such record content: application/json: schema: $ref: '#/components/schemas/Error' '429': description: Rate limited. Retry after the interval in `Retry-After`. content: application/json: schema: $ref: '#/components/schemas/Error' security: - bearerAuth: [] components: schemas: UpdateAgent: type: object properties: name: type: string minLength: 1 maxLength: 200 system_prompt: type: string minLength: 1 maxLength: 20000 description: >- The agent's instructions. Spoken conversation, so keep it short and concrete. opening_message: type: string minLength: 1 maxLength: 1000 description: >- Spoken as soon as the call connects. Supports {{name}} style merge fields. Required — an agent without one answers in silence. voice: allOf: - $ref: '#/components/schemas/VoiceConfig' - type: object language: type: string default: en-US knowledge_base_id: type: string pattern: ^[0-9a-f]{24}$ example: 6a96a3ead6e886d42462dd3e outbound_phone_number_id: type: string pattern: ^[0-9a-f]{24}$ example: 6a96a3ead6e886d42462dd3e appointment_booking_enabled: type: boolean default: false Agent: type: object properties: id: type: string pattern: ^[0-9a-f]{24}$ example: 6a96a3ead6e886d42462dd3e object: type: string enum: - agent name: type: string system_prompt: type: string opening_message: type: - string - 'null' voice: $ref: '#/components/schemas/VoiceConfig' language: type: string knowledge_base_id: type: - string - 'null' pattern: ^[0-9a-f]{24}$ example: 6a96a3ead6e886d42462dd3e outbound_phone_number_id: type: - string - 'null' pattern: ^[0-9a-f]{24}$ example: 6a96a3ead6e886d42462dd3e appointment_booking_enabled: type: boolean created_at: type: string format: date-time description: ISO 8601, always UTC. example: '2026-09-01T12:00:00.000Z' required: - id - object - name - system_prompt - opening_message - voice - language - knowledge_base_id - outbound_phone_number_id - appointment_booking_enabled - created_at Error: type: object properties: error: type: object properties: type: type: string enum: - invalid_request_error - authentication_error - permission_error - rate_limit_error - insufficient_credits - not_found_error - conflict_error - api_error code: type: string description: Stable machine-readable code. example: agent_not_found message: type: string description: >- Human-readable explanation. Do not match on this — match on code. param: type: string description: Which field caused the failure, when applicable. doc_url: type: string request_id: type: string description: Quote this when asking for help. example: req_01HXYZ... required: - type - code - message - request_id required: - error VoiceConfig: type: - object - 'null' properties: stt: $ref: '#/components/schemas/SttConfig' llm: $ref: '#/components/schemas/LlmConfig' tts: $ref: '#/components/schemas/TtsConfig' realtime: $ref: '#/components/schemas/RealtimeConfig' turn_taking: $ref: '#/components/schemas/TurnTaking' description: >- Either a composed pipeline (stt + llm + tts) or a single realtime model. Not both. SttConfig: type: object properties: model: type: string pattern: ^[a-z0-9_-]+\/[a-zA-Z0-9._-]+$ example: deepgram/nova-3 language: type: string default: en-US description: BCP-47 tag, or "multi" for automatic detection. endpointing_ms: type: integer minimum: 50 maximum: 3000 description: >- Silence before a turn is considered finished. Lower is snappier and more prone to cutting people off. required: - model LlmConfig: type: object properties: model: type: string pattern: ^[a-z0-9_-]+\/[a-zA-Z0-9._-]+$ example: openrouter/gpt-4o-mini temperature: type: number minimum: 0 maximum: 2 max_tokens: type: integer minimum: 1 maximum: 4096 description: >- Caps reply length. Long replies cost the caller waiting time as well as money. required: - model TtsConfig: type: object properties: model: type: string pattern: ^[a-z0-9_-]+\/[a-zA-Z0-9._-]+$ example: elevenlabs/eleven_turbo_v2_5 voice: type: string example: 21m00Tcm4TlvDq8ikWAM stability: type: number minimum: 0 maximum: 1 similarity_boost: type: number minimum: 0 maximum: 1 speed: type: number minimum: 0.5 maximum: 2 required: - model RealtimeConfig: type: object properties: model: type: string pattern: ^[a-z0-9_-]+\/[a-zA-Z0-9._-]+$ example: google/gemini-live voice: type: string example: Charon language: type: string default: auto required: - model TurnTaking: type: object properties: interrupt_sensitivity: type: string enum: - low - normal - high default: normal description: How readily the agent stops talking when the caller speaks. silence_wait_ms: type: integer minimum: 100 maximum: 5000 securitySchemes: bearerAuth: type: http scheme: bearer description: >- Your Wixzel Voice API key: `Authorization: Bearer wv_live_...`. Keys are scoped; grant only what the integration needs. ````