How to Use Describe an Extension in Safari on iOS 27

iOS 27 adds a Safari feature called Describe an Extension, shown as Describe Extension in the menu, that lets you create a custom Safari extension by describing what you want in plain English. Before it existed you had to download an extension from the App Store or build one yourself with Xcode, HTML, CSS, and JavaScript.

The steps below cover where to find it on iPhone, iPad, and Mac, what to type, and how to change an extension after Safari builds it. It sits alongside Notify Me and automatic tab organization in the new Safari features.

Describe an Extension in Safari on iOS 27

Describe an Extension Needs an iPhone 15 Pro or Newer

The feature relies on Apple Intelligence. It is available on iPhone 15 Pro, iPhone 15 Pro Max, and iPhone 16 models or later running iOS 27, so an iPhone 15 or older will not get it even though it can run iOS 27.

Apple Intelligence is not available in every language or region, and usage limits may apply.

How to Use Describe an Extension in Safari on iPhone

Open Safari and go to the webpage you want to create an extension for.
Tap the page menu button in the address bar.
Tap Describe Extension.
Tap one of the suggested categories, or type what you want the extension to do in your own words.
If no existing extension matches, tap Create and Safari builds one.
Try the extension on the page, then save it if it does what you wanted.

Create a custom Safari extension on iPhone in iOS 27

Safari checks the App Store first to see whether a matching extension already exists. If one does the job you can install it, and if not, keep your description and tap Create.

Describe an Extension Also Works in Safari on iPad and Mac

On iPad, open Safari, go to the page, tap the page menu button, and tap Describe Extension. On a Mac running macOS 27 Golden Gate, click the page menu button in the Smart Search field and choose Describe Extension.

Both use Apple Intelligence, so the same language, region, and usage limits apply.

Four Prompt Categories Give You Ideas to Start From

Apple groups its suggestions into Boost Productivity, Improve Focus, Get Creative, and Develop and Design. Tapping a category shows sample prompts you can use as they are or change.

Safari Describe Extension prompt categories

These are examples of what people can ask for:

Create a citation for the current webpage and copy it to my clipboard
Create a 3-minute focus timer for the page
Set the minimum font size to 14pt
Style websites like 90s websites with bold colors and type
Highlight and show the dimensions of webpage elements when I tap on them

Simple page changes are the safest first tries, such as recoloring a background or turning every picture on a page black and white.

Edit an Extension Until It Behaves the Way You Want

The first result does not always match what you pictured. Safari lets you try the extension on the page before it becomes part of your browser, and you can tap Edit to describe what to change without starting over.

Extensions You Create Sync Through iCloud and Can Be Turned Off Anytime

An extension you create on one device syncs to your other devices signed in with the same Apple Account, so you do not need to build it again on your iPad or Mac.

You can turn any Safari extension on or off at any time. If you use Safari profiles, turn the extension on for each profile where you want it.

Common Questions About Describe an Extension

Why Don’t I See Describe Extension in Safari?

Check that your iPhone is an iPhone 15 Pro, iPhone 15 Pro Max, or an iPhone 16 model or later, that it runs iOS 27, and that Apple Intelligence is available in your language and region. Without all three, the option will not appear.