> ## Documentation Index > Fetch the complete documentation index at: https://docs.kejue.co/llms.txt > Use this file to discover all available pages before exploring further. # Attach Tool > Attach a tool to an agent. ## OpenAPI ````yaml /openapi.json post /agents/{agent_id}/tools openapi: 3.1.0 info: title: Kejue Public API description: >- The Kejue Public API lets you programmatically create calls, manage campaigns, and retrieve call results. ## Authentication All requests require an API key passed in the `X-API-Key` header: ``` X-API-Key: kej_live_... ``` API keys are scoped to a workspace. Create and manage keys from the Kejue dashboard under **Settings → API Keys**. ## Base URL ``` https://api.kejue.co/api/v1 ``` ## Rate Limits API requests are rate-limited per workspace. If you exceed the limit you'll receive a `429 Too Many Requests` response. ## Errors All error responses follow a consistent format: ```json { "error": "Human-readable message", "code": "ERROR_CODE", "details": {} } ``` version: 1.0.0 servers: - url: https://api.kejue.co/api/v1 description: Production security: - ApiKeyAuth: [] tags: - name: Agents description: >- Create and manage AI agents (personas). Each agent has a name, prompt, voice configuration, and optional tools. Agents are the core building block — attach voice configs, tools, and use them to make calls. - name: Calls description: >- Create outbound calls, retrieve call details and transcripts, and list calls with filtering. Each call is associated with a contact and optionally an agent and campaign. - name: Persona Calls description: >- Create calls with the full agent configuration pre-loaded. Applies the complete settings hierarchy (workspace → agent → campaign → overrides) with all agent tools, tags, scoring, and webhooks inherited automatically. - name: Contacts description: >- Create and manage contacts. Contacts represent the people your agents call. Each contact has a phone number, name, and optional metadata. Supports single creation, bulk import, and CSV upload. - name: Campaigns description: >- Create and manage calling campaigns. Campaigns let you batch-call a list of contacts with shared settings, scheduling, and retry logic. - name: Tools description: >- Create and manage custom HTTP tools that agents can invoke during calls. Tools let agents fetch data, trigger actions, or integrate with external systems mid-conversation. Each tool supports three parameter types: - **Dynamic parameters** — filled by the AI at runtime (visible to the AI) - **Static parameters** — fixed values sent with every invocation (hidden from the AI) - **System parameters** — values injected from the execution context at runtime, such as `call_id`, `contact_id`, or `workspace_id` (hidden from the AI) - name: Voices description: List available voices for use in agent voice configurations. - name: Phone Numbers description: List phone numbers available in your workspace for making outbound calls. - name: Webhooks description: >- Create and manage webhook subscriptions. Receive real-time notifications for call events (started, ended, etc.) at your specified URL. - name: Models description: List available AI models for use in agent voice configurations. paths: /agents/{agent_id}/tools: post: tags: - Agents summary: Attach Tool description: Attach a tool to an agent. operationId: attach_tool_agents__agent_id__tools_post parameters: - name: agent_id in: path required: true schema: type: string title: Agent Id requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AgentToolAttach' responses: '201': description: Successful Response content: application/json: schema: $ref: '#/components/schemas/AgentToolResponse' '401': description: >- Missing or invalid API key. Pass a workspace API key in the `X-API-Key` header. content: application/json: example: error: Invalid or missing API key code: UNAUTHORIZED details: {} schema: $ref: '#/components/schemas/ErrorResponse' '404': description: Agent not found in this workspace. content: application/json: example: error: Agent not found code: NOT_FOUND details: agent_id: non_existent_id schema: $ref: '#/components/schemas/ErrorResponse' '409': description: The named tool is already attached to this agent. content: application/json: example: error: Tool 'send_email' is already attached to this agent code: CONFLICT details: {} schema: $ref: '#/components/schemas/ErrorResponse' '422': description: Request body or query parameters failed validation. content: application/json: example: error: Validation failed code: VALIDATION_ERROR details: errors: - field: body.name message: Field required type: missing schema: $ref: '#/components/schemas/ErrorResponse' security: - ApiKeyAuth: [] components: schemas: AgentToolAttach: properties: tool_name: type: string title: Tool Name description: Tool name — custom tool name or builtin name tool_id: anyOf: - type: string - type: 'null' title: Tool Id description: Tool ID — required for custom HTTP tools channels: items: type: string type: array title: Channels description: >- Channels where the tool is active: 'voice:in-call', 'voice:post-call', 'whatsapp' default: - voice:in-call config: additionalProperties: true type: object title: Config description: >- Tool-specific configuration. The shape depends on the tool — see the Tools guide for the full schema of each builtin. **Examples for selected builtins:** `agent_transfer` — transfer the live call to a different persona: ```json { "targets": [ { "key": "billing", "persona_id": "", "voice_config_id": "", "when_to_use": "Caller has questions about invoices, refunds, or payments." }, { "key": "tech_support", "persona_id": "", "when_to_use": "Caller is reporting a technical issue with the product." } ] } ``` `create_call` — create a new outbound call from inside a conversation: ```json { "default_persona_id": "", "default_context": "Follow-up call about the contact's inquiry.", "allow_persona_override": false } ``` type: object required: - tool_name title: AgentToolAttach description: Attach a tool to an agent. AgentToolResponse: properties: tool_name: type: string title: Tool Name tool_id: anyOf: - type: string - type: 'null' title: Tool Id channels: items: type: string type: array title: Channels config: additionalProperties: true type: object title: Config type: object required: - tool_name - channels - config title: AgentToolResponse description: A tool attached to an agent. ErrorResponse: properties: error: type: string title: Error code: type: string title: Code details: anyOf: - additionalProperties: true type: object - type: 'null' title: Details type: object required: - error - code title: ErrorResponse description: Standard error response. example: code: NOT_FOUND details: contact_id: '123' error: Contact not found securitySchemes: ApiKeyAuth: type: apiKey in: header name: X-API-Key description: Workspace API key (e.g. `kej_live_...`) ````