Shopify Sidekick App Extensions: Data vs Action, and What to Build First

Sidekick, the AI assistant inside the Shopify admin, can now read data from third-party apps and send merchants to the right place inside them. Any app developer can build these Sidekick app extensions. This guide explains the two extension types, shows the CLI commands and config you need, and gives our view on what to build first. Checked against Shopify’s developer documentation in October 2026.

What Shopify Sidekick App Extensions Are

There are two types, and Shopify’s changelog describes both.

• App data. Your app’s content becomes searchable in Sidekick. A merchant can ask for their best-performing email subject lines, and Sidekick returns relevant campaigns from your app with key metrics.
• App actions. Sidekick navigates the merchant to the right page in your app, pre-filled with context, so they confirm before any change is made.

The Spring ’26 Edition launched app extensions with more than 15 partners, including Klaviyo, Loop, Smile, Judge.me, Matrixify, Seguno and Yotpo. Shopify also reports that weekly active shops using Sidekick grew 4x year over year in Q1.

Build a Data Extension

First add an extensions_summary to your shopify.app.toml. Then scaffold the extension with the Shopify CLI.

shopify app generate extension --template app_data --name tools

In shopify.extension.toml, add a description and, optionally, a link to instructions that tell Sidekick how to use the extension. The target is special: it is not tied to a Shopify resource and runs headlessly.

target = "admin.app.tools.data"

A data extension must only retrieve data. It should never change anything in your app. The full walkthrough is in Shopify’s guide to surfacing app data.

Build an Action Extension

Actions start from a different template. The docs example uses an app action link.

shopify app generate extension --template app_action_link --name open-email

Set the name, handle and type in shopify.extension.toml, then add an intents configuration with an action, a type and a schema. The docs example uses an edit action. Pick the extension type by app shape: an admin link supports embedded apps only, while a UI extension supports both embedded and non-embedded apps. See surfacing app actions for the details.

One hard limit applies to both types. You can register a maximum of 20 tools per app, shared across all data and action extensions.

Write Descriptions Sidekick Can Route On

Shopify’s docs include a section on writing effective extension descriptions, and it deserves your time. Our reading: the description is how Sidekick decides whether your tool answers a merchant’s question. Write it in the merchant’s words, say exactly which question or task it covers, and say what it does not cover.

Our Analysis: What to Build First

Start with data, not actions. A data extension is retrieval-only, so the risk is low, and it answers questions merchants already ask, such as which campaign did best. Actions change state, even with a confirmation step, so they need more testing.

The 20-tool budget forces prioritization. Data and actions share one limit. List the ten questions and tasks merchants bring to your support team most often and cover those, not your whole API.

Distribution is the prize, with a catch. Sidekick is becoming a surface where merchants meet your app without opening it. Data extensions can leave a merchant with an answer and no reason to visit your interface. Action extensions send them into your app and keep engagement. If your upsells or pricing depend on in-app visits, favor actions for your highest-value flows.

Budget for QA and support. Another interface is another place your app can be wrong, and a wrong answer in Sidekick will be blamed on your app. Test with real merchant phrasing, not only your own test questions.

Sidekick is one half of Shopify’s AI push. The other half is how shoppers’ agents find products, covered in Shopify Agentic Storefronts: get your catalog ready.

This article is part of our Shopify Agentic Commerce guide.

FAQ about Shopify Sidekick App Extensions

Can any developer build one? Yes. Shopify’s changelog says all app developers can build Sidekick app extensions.

Does Sidekick change data without asking? For app actions, Shopify says the merchant confirms before any change is made.

Do extensions work with non-embedded apps? UI extensions do. Admin link extensions support embedded apps only.

Related: Building for agents beyond Sidekick? See Shopify Checkout WebMCP.