> ## 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.
# 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. give the agent context to inform the rest of the phone call
2. change the agent’s behavior based on the pulled information
3. run functions/tasks outside the call
## How it Works
### Configuring an External Action with `ExecuteExternalActionVocodeActionConfig`
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`!
#### Overview
* `processing_mode`: We currently only support `muted`, which makes the agent silent while processing the request.
* `name`: the name of the external action -- this has no impact on the functionality of action itself.
* `description`: Used by the Function Calling API to determine when to make the External Action call itself. See the [`description` field section below](/open-source/external-action#description-field) for more info!
* `url`: The API request is sent to this URL in the format
defined below in [Responding to External Action API Requests](/open-source/external-action#input-schema-field)
* `input_schema`: A [JSON Schema](https://json-schema.org/) for the payload to send to the External API. See the [`input_schema` field section below](/open-source/external-action#responding-to-external-action-api-requests) for more info!
* `speak_on_send`: if `True`, then the underlying LLM will generate a message to be spoken as the
API request is being sent.
* `speak_on_receive`: if `True`, then the agent will speak once it receives a result from the API Response. If the response does not contain an `agent_message` (see [Response Formatting](#response-formatting)), the agent will query the LLM for the message to speak.
* `signature_secret`: a base64 encoded string to enable request validation, see the [Signature Validation section](/open-source/external-action#signature-validation) below for more info
#### `input_schema` Field
The `input_schema` field is a [JSON Schema](https://json-schema.org/) form the payload to send to the External API.
For example, in the [Meeting Assistant Example](/open-source/external-action#meeting-assistant-example) below we formed the following JSON schema:
```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! Vocode treats OpenAI Function Calling as a first-class standard 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](/open-source/external-action#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 functions are triggered and queried,
so we recommend treating it similar to prompting for an LLM!
### 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](/open-source/external-action#configuring-an-external-action-with-executeexternalactionvocodeactionconfig)
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 specifically matches `input_schema`. Using the [Meeting Assistant Example](/open-source/external-action#meeting-assistant-example) below, the request will contain:
```bash theme={null}
POST url HTTP/1.1
Accept: application/json
Content-Type: application/json
x-vocode-signature:
{
"payload": {
"length": "30m",
"time": "10:30am"
}
}
```
#### Signature Validation
A cryptographically signed signature of the request body and a randomly generated byte hash is included as a header (under `x-vocode-signature`) in the outbound request, so the receiving API can validate the identity of the incoming request. The signature secret is used to sign the request and ensure the validity of the `x-vocode-signature` field, and therefore *must be securely managed*.
This should be set as a base64-encoded string and we recommend a longer length as well, using the following snippet as an example:
```python theme={null}
import os
import base64
signature_secret = base64.b64encode(os.urandom(32)).decode()
```
Use the following code snippet to check the signature in an inbound request:
```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 secret for the action (make sure this is stored securely).
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(), hashlib.sha256).digest()
assert hmac.compare_digest(decoded_digest, calculated_digest) is True
```
#### Response Formatting
Vocode expects responses from the user’s API in JSON in the following format:
```python theme={null}
Response {
result: Any
agent_message: Optional[str] = None
}
```
* `result` is a payload containing the result of the action on the user’s side, and can be in any format
* `agent_message` optionally contains a message that will be synthesized into audio and sent back to the phone call. Note this means the LLM will not be queried to send a message (see [Configuring the External Action](/open-source/external-action#configuring-an-external-action-with-executeexternalactionvocodeactionconfig) above for more info)
In the [Meeting Assistant Example](/open-source/external-action#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"
}
```
## EA Local Response Server Example:
The following is an example of a quick start to enable testing external actions locally.
Running `fastapi dev app.py` will run the server @ `http://127.0.0.1:8000` and can be used for external actions locally!
```python app.py theme={null}
import asyncio
import base64
import hashlib
import hmac
import json
import time
from fastapi import FastAPI, HTTPException, Request, status
from pydantic import BaseModel
app = FastAPI()
action_secret = ""
def is_signature_valid(request: Request, json_payload: dict):
signature_secret_as_bytes = base64.b64decode(action_secret)
decoded_digest = base64.b64decode(request.headers.get("x-vocode-signature"))
calculated_digest = hmac.new(
signature_secret_as_bytes, json.dumps(json_payload).encode(), hashlib.sha256
).digest()
return hmac.compare_digest(decoded_digest, calculated_digest)
@app.post("/external_action")
def update_item(request: Request):
json_payload = asyncio.run(request.json())
print(json_payload)
if not is_signature_valid(request, json_payload):
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Signature verification failed for payload",
)
time.sleep(3)
return {
"result": {"success": True},
}
```
```txt requirements.txt theme={null}
pydantic==2.*
fastapi==0.111.*
```
## Meeting Assistant Example
This is an example of how to create an action config 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}
import json
import base64
import os
from vocode.streaming.action.execute_external_action import (
ExecuteExternalAction,
ExecuteExternalActionVocodeActionConfig,
)
ACTION_INPUT_SCHEMA = {
"type": "object",
"properties": {
"length": {
"type": "string",
"enum": ["30m", "1hr"],
},
"time": {
"type": "string",
"pattern": "^\d{2}:\d0[ap]m$",
},
},
}
action_config = ExecuteExternalActionVocodeActionConfig(
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 = json.dumps(ACTION_INPUT_SCHEMA),
signature_secret = base64.b64encode(os.urandom(32)).decode(),
)
```
See [Action Agents](/open-source/action-agents#using-your-action-and-action-factory-in-an-agent) for an example of how to use this action config with an agent in a conversation.
Note that you do not need to create a custom action factory, since `DefaultActionFactory` already supports external actions.