> ## Documentation Index
> Fetch the complete documentation index at: https://aci.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Function (Tool)

> A Function is a callable operation that belongs to an App

Function in our platform is equivalent to the concept of `Function` or `Tool` in function/tool calling.
Functions are logically grouped by the App they belong to.

<Frame>
  <img src="https://mintcdn.com/aipotheosislabs-60d5bdcb/d29fRbieQpqSnjGv/images/platform/functions.png?fit=max&auto=format&n=d29fRbieQpqSnjGv&q=85&s=0b36fa69361e8539413a431a751e8af8" alt="Function Concept Illustration" width="2508" height="800" data-path="images/platform/functions.png" />
</Frame>

## Each Function:

* Have a unique name across the platform, typically in the format `APP_NAME__FUNCTION_NAME` (e.g., "GITHUB\_\_STAR\_REPOSITORY")
* Is compatible with function calling schema of OpenAI, Anthropic etc
* Define the parameters they accept and the response they return
* Handle the communication with external services
* Inherit the authentication configuration from the App

<Note>
  Functions are the building blocks that AI agents use to interact with external services. Each function has a specific purpose, such as creating a GitHub repository or sending a Slack message.
</Note>