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

# Tools

> External actions your assistants can call to get work done.

## Overview

<Frame>
  <img src="https://mintcdn.com/phinite/spbPnSZPWmAXAKhH/images/Tools-1.png?fit=max&auto=format&n=spbPnSZPWmAXAKhH&q=85&s=074da7f164a9e4f39ccac8eeeb0e496b" alt="Tools 1" width="1918" height="879" data-path="images/Tools-1.png" />
</Frame>

Tools are modular logic units that developers maintain and reuse across Assistants. Tools are built and versioned in [DevStudio](/devstudio/overview). Agents invoke tools to perform actions.

### Managed in DevStudio

Developers can:

* Edit and test tools in isolation.
* Save tools to the **Workspace Library** for reuse.
* Version and publish them for other assistants.
  > Tools used in multiple assistants should always be version-controlled.\
  > Breaking changes must be tested in Dev before UAT or Prod.

## Structure

* Parameters and input validation
* Return schema and capture variables
* Versioning and publishing

## Best practices

* Defensive error handling
* Secure authentication
* Return only the required data in the output to minimize token consumption, as the response is passed directly to the agent.
* Clear parameter docs and examples