Extend with code

Write Python functions to extend your agent beyond what the visual interface covers — call APIs, query databases, validate input, and encode custom business logic. The agent invokes your function like any other tool.

Python required. Non-technical operators: see Configure agents in the UI for the no-code path.

Before writing custom API code, check if a pre-built integration already exists for your platform (e.g., Salesforce, Zendesk, OpenTable, Stripe). Pre-built integrations handle authentication, environment configuration, and common operations for you.

What you can build

API integrations

Call external APIs to look up bookings, check availability, or retrieve account details

Validate input, calculate pricing, or enforce rules that the LLM cannot handle alone

CRM and data writes

Create records, update customer profiles, or log interactions in external systems

Dynamic routing

Route calls to the right team based on real-time data or custom logic

Multi-step workflows

Build code-driven flows with transition functions for complex conversation paths

Real-time configuration

Define schemas that adapt agent behavior based on external config data

Get started

Write your first function

Follow the create a function guide to set up a Python function with parameters, code, and a description the LLM can use to trigger it.

Understand the tools system

Read the tools overview to learn how functions integrate with the LLM, how to use conv objects, and best practices for naming and triggering.

Explore advanced patterns

Read flows, call handoffs, and secrets management to build production integrations.

Tools and functions

Write Python scripts that run when your agent needs to take action. Functions are the bridge between conversation and your business systems.

Create a function

Set up a function with naming conventions, parameters, and Python code

Initialize conversation context before the greeting plays

Run post-call processing after a conversation ends

Control agent behavior with string and dictionary returns

Define, update, and persist values across turns

Standard and non-standard libraries available in your functions

Add filler phrases to avoid silence during slow functions

Use functions in topics

Trigger functions from FAQs

Reference

Access conversation data and built-in utilities in your functions.

Conversation states, flows, and telephony attributes

Structured diagnostics and PII-scoped logging

Built-in helpers for addresses, cities, and structured data

Call configured API integrations

Persistent data across conversations for repeat callers

Function classes

VoiceWeighting, TTSVoice, and provider classes

Advanced capabilities

Store API keys and credentials securely

Configure call transfers and routing rules

Configuration builder

Define real-time config schemas for dynamic agent behavior

Call data export

Access transcripts and recordings through the API

Code-driven flows

Build flows with transition functions and programmatic control

Script agent configuration

Use the Agents API to create, configure, and deploy agents from code

Integrate with PolyAI REST APIs for chat, conversations, alerts, and more