Advanced Features
Custom Tools
Extend your AI's capabilities with custom function calling tools.
Custom tools allow your AI to perform actions beyond just answering questions. Connect to external APIs, fetch live data, submit forms, or integrate with your existing business systems.
What are Tools?
Tools are functions that the AI can call during a conversation. When a user asks something that requires external data or actions, the AI will:
- 1
Recognize the need
The AI identifies that it needs external data to answer
- 2
Call the tool
It invokes your custom tool with the appropriate parameters
- 3
Process the response
The tool executes and returns data to the AI
- 4
Formulate answer
The AI uses the data to provide a natural response
Example Use Cases
Package Tracking
"Where is my order?" → Fetches shipping status from your logistics API
Inventory Check
"Is this in stock?" → Queries your inventory system for real-time availability
Booking System
"Book a demo" → Creates appointments in your calendar system
CRM Integration
"Update my contact info" → Modifies customer records in your CRM
Creating a Custom Tool
Tools are defined in JSON format with the following structure:
{
"name": "track_package",
"description": "Track a package by its tracking number",
"parameters": {
"type": "object",
"properties": {
"tracking_number": {
"type": "string",
"description": "The package tracking number"
}
},
"required": ["tracking_number"]
},
"endpoint": "https://your-api.com/track",
"method": "GET"
}Tool Properties
| Property | Description |
|---|---|
name | Unique identifier for the tool (snake_case) |
description | Explains when and why to use this tool |
parameters | JSON Schema defining the tool's input parameters |
endpoint | URL to call when the tool is invoked |
method | HTTP method (GET, POST, PUT, DELETE) |
Built-in Tools
hej! comes with several built-in tools that are always available:
search_knowledge
Searches your indexed website content for relevant information
get_document
Retrieves a specific page's content by URL
Best Practices
Write clear descriptions
The AI uses descriptions to decide when to call tools. Be specific about the tool's purpose.
Return structured data
Your endpoints should return clean JSON that's easy for the AI to interpret.
Handle errors gracefully
Return meaningful error messages that help the AI explain issues to users.
Secure your endpoints
Use authentication and rate limiting to protect your APIs from abuse.
Plan Availability
Custom tools are available on Business, Pro, and Enterprise plans. Built-in search tools are available on all plans.