> ## Documentation Index > Fetch the complete documentation index at: https://docs.vocode.dev/llms.txt > Use this file to discover all available pages before exploring further. # [Beta] External Actions > Have your agent communicate with an External API External Actions allow Vocode agents to take actions outside the realm of a phone call. In particular, Vocode agents can decide to *push* information to external systems via an API request, and *pull* information from the API response in order to: 1. change the agent’s behavior based on the pulled information 2. give the agent context to inform the rest of the phone call ## How it Works ### Configuring the External Action The Vocode Agent will determine after each turn of conversation if its the ideal time to interact with the External API based primarily on the configured External Action's `description` and `input_schema`! #### `input_schema` Field The `input_schema` field is a [JSON Schema](https://json-schema.org/) object that instructs how to properly form a payload to send to the External API. For example, in the [Meeting Assistant Example](/external-actions#meeting-assistant-example) below we formed the following JSON payload: ```json theme={null} { "type": "object", "properties": { "length": { "type": "string", "enum": ["30m", "1hr"] }, "time": { "type": "string", "pattern": "^d{2}:d0[ap]m$" } } } ``` This is stating the External API is expecting: * Two fields * `length` (string): either "30m" or "1hr" * `time` (string): a regex pattern defining a time ending in a zero with `am`/`pm` on the end ie: `10:30am` If you’re noticing that this looks very familiar to OpenAI function calling, it is! The Vocode API treats OpenAI LLMs as first-class and uses the function calling API when the agent uses an OpenAI LLM. The lone difference is that the top level `input_schema` JSON schema must be an `object` - this is so we can use JSON to send over parameters to the user’s API. #### `description` Field The `description` is best used to descibe your External Action's purpose. As its passed through directly to the LLM, its the best way to convey instructions to the underlying Vocode Agent. For example, in the [Meeting Assistant Example](/external-actions#meeting-assistant-example) below we want to book a meeting for 30 minutes to an hour so we set the description as `Book a meeting for a 30 minute or 1 hour call.` The `description` field is passed through and heavily affects how we do our function decisioning so we recommend treating it in the same way you would a prompt to an LLM! #### Other Fields to Determine Agent Behavior * `speak_on_send`: if `True`, then the underlying LLM will generate a message to be spoken into the phone call as the API request is being sent. - `url`: The API request is sent to this URL in the format defined below in [Responding to External Action API Requests](/external-actions#responding-to-external-action-api-requests) * `speak_on_receive`: if `True`, then the Vocode Agent will invoke the underlying LLM to respond based on the result from the API Response or the Error encountered. ### Responding to External Action API Requests Once an External Action has been created, the Vocode Agent will issue API requests to the defined `url` during the course of a phone call based on the [configuration noted above](/external-actions#configuring-the-external-action) The Vocode API will wait a maximum of *10 seconds* before timing out the request. In particular, Vocode will issue a POST request to `url` with a JSON payload that matches `input_schema` , specifically (using the [Meeting Assistant Example](/external-actions#meeting-assistant-example) below): ```bash theme={null} POST url HTTP/1.1 Accept: application/json Content-Type: application/json x-vocode-signature: { "call_id": , "payload": { "length": "30m", "time": "10:30am" } } ``` #### Signature Validation A cryptographically signed signature of the request body and a randomly generated byte hash in included as a header (under `x-vocode-signature`) in the outbound request so that the user’s API can validate the identity of the incoming request. The signature secret is contained in the External Action's API object and can be found when creating an object (as noted below in the [Meeting Assistant Example](/external-actions#meeting-assistant-example)), or by getting the API object via the `/v1/actions?id=ACTION_ID` endpoint: ```bash Example cURL Request theme={null} curl --request GET \ --url https://api.vocode.dev/v1/actions?id=\ --header 'Content-Type: application/json' \ --header 'Authorization: Bearer ' ``` ```json Response theme={null} { "id": "", "user_id": "ecd792cf-18a2-420b-91f5-cdaf22f5f562", "type": "action_external", "config": { "processing_mode": "muted", "name": "Meeting_Booking_Assistant", "description": "Book a meeting for a 30 minute or 1 hour call.", "url": "http://example.com/booking", "input_schema": { "type": "object", "properties": { "length": { "type": "string", "enum": ["30m", "1hr"] }, "time": { "type": "string", "pattern": "^\\d{2}:\\d0[ap]m$" } } }, "speak_on_send": true, "speak_on_receive": true, "signature_secret": "MX/9/+iblnUoAAM2Jft8sgeY1bevJvuih2nr7XKPHIY=" }, "action_trigger": { "type": "action_trigger_function_call", "config": {} } } ``` Use the following code snippet to check the signature in an inbound request: ```python Python theme={null} import base64 import hashlib import hmac async def test_requester_encodes_signature( request_signature_value: str, signature_secret: str, payload: dict ): """ Asynchronous function to check if the request signature is encoded correctly. Args: request_signature_value (str): The request signature to be decoded. signature_secret (str): The signature to be decoded and used for comparison. payload (dict): The payload to be used for digest calculation. Returns: None """ signature_secret_as_bytes = base64.b64decode(signature_secret) decoded_digest = base64.b64decode(request_signature_value) calculated_digest = hmac.new(signature_secret_as_bytes, json.dumps(payload).encode("utf-8"), hashlib.sha256).digest() assert hmac.compare_digest(decoded_digest, calculated_digest) is True ``` ```typescript TypeScript theme={null} import * as crypto from 'crypto'; async function testRequesterEncodesSignature( requestSignatureValue: string, signatureSecret: string, payload: Record ): Promise { /** * Asynchronous function to check if the request signature is encoded correctly. * * @param requestSignatureValue - The request signature to be decoded. * @param signatureSecret - The signature to be decoded and used for comparison. * @param payload - The payload to be used for digest calculation. */ const signatureAsBytes = Buffer.from(signatureSecret, 'base64'); const decodedDigest = Buffer.from(requestSignatureValue, 'base64'); const payloadString = JSON.stringify(payload); const calculatedDigest = crypto .createHmac('sha256', signatureAsBytes) .update(payloadString) .digest(); if (!crypto.timingSafeEqual(decodedDigest, calculatedDigest)) { throw new Error('Signature mismatch'); } } ``` #### Response Formatting Vocode expects responses from the user’s API in JSON in the following format: ```python theme={null} Response { result: Dict[str, Any] agent_message: Optional[str] = None } ``` * `result` is a payload containing the result of the action on the user’s side, and can have any schema * `agent_message` optionally contains a message that will be synthesized into audio and sent back to the phone call (see [Configuring the External Action](/external-actions#configuring-the-external-action) above for more info) In the [Meeting Assistant Example](/external-actions#meeting-assistant-example) below, the user’s API could return back a JSON response that looks like: ```json theme={null} { "result": { "success": true }, "agent_message": "I've set up a calendar appointment at 10:30am tomorrow for 30 minutes" } ``` ## Meeting Assistant Example: This is an example of a Meeting Assistant which will attempt to book a meeting for 30 minutes or an hour at any time ending in a zero (ie 10:30am is okay but 10:35am is not) ```python Python theme={null} vocode_client.actions.create_action( request={ "type": "action_external", "config": { "name": "Meeting_Booking_Assistant", "description": ("Book a meeting for a 30 minute or 1 hour call."), "url": "http://example.com/booking", "speak_on_send": True, "speak_on_receive": True, "input_schema": { "type": "object", "properties": { "length": { "type": "string", "enum": ["30m", "1hr"], }, "time": { "type": "string", "pattern": "^\d{2}:\d0[ap]m$", }, }, }, }, }, ) ``` ```typescript TypeScript theme={null} const action = await vocode.actions.createAction({ type: "action_external", config: { name: "Meeting_Booking_Assistant", description: "Book a meeting for a 30 minute or 1 hour call.", url: "http://example.com/booking", speak_on_send: true, speak_on_receive: true, input_schema: { type: "object", properties: { length: { type: "string", enum: ["30m", "1hr"], }, time: { type: "string", pattern: "^\\d{2}:\\d0[ap]m$", }, }, }, }, }); ``` ```bash cURL theme={null} curl --request POST \ --url https://api.vocode.dev/v1/actions/create \ --header 'Content-Type: application/json' \ --header 'Authorization: Bearer ' \ --data '{ "type": "action_external", "config": { "name": "Meeting_Booking_Assistant", "description": "Book a meeting for a 30 minute or 1 hour call.", "url": "http://example.com/booking", "speak_on_send": true, "speak_on_receive": true, "input_schema": { "type": "object", "properties": { "length": { "type": "string", "enum": ["30m", "1hr"] }, "time": { "type": "string", "pattern": "^\\d{2}:\\d0[ap]m$" } } } } }' ``` If you're looking to attach the created External Action to your agent after creating it in the example below, theres an example of how to do this on the [Using Actions](/using-actions#transfercall) page under the TransferCall section!