# Run and share a preview

> Open the service an agent is building and give feedback.

Source: https://usefiretower.com/docs/previews

Ask the agent to start the application and tell you its port. Open the workspace, then click the globe button, **Preview a port**.

![The workspace preview button and port picker](https://usefiretower.com/product/guide-previews-page-light.webp)

The workspace preview button and port picker. Desktop app · sample data. Select to enlarge.

## 1\. Open the running application

Enter the port, such as **3000**, and click **Open**. The preview appears in a tab beside the conversation. Firetower routes it through the control plane; the worker does not need a public port.

![The running application inside Firetower](https://usefiretower.com/product/guide-preview-open-light.webp)

The running application inside Firetower. Desktop app · sample data. Select to enlarge.

Use **Full width**, **Tablet** or **Phone** to check different layouts.

## 2\. Annotate the page

Click **Annotate**, then click an element in the application. Describe what should change and click **Keep this note**.

![Writing a note on the preview’s checkout button](https://usefiretower.com/product/guide-preview-annotate-light.webp)

Writing a note on the preview’s checkout button. Desktop app · sample data. Select to enlarge.

## 3\. Send the notes and check the result

![Preview notes ready to send to the agent](https://usefiretower.com/product/guide-preview-notes-light.webp)

Preview notes ready to send to the agent. Desktop app · sample data. Select to enlarge.

Review the notes in the right panel. Click **Send notes to the agent**; the button shows how many notes will be sent. After the agent makes the change, reload the preview and check it.

## Share access

A preview uses a signed URL. Anyone opening it still needs a network route to your Firetower installation. The application’s own sign-in may also apply.

## If the preview stops

Check that the service is running on the selected port and the worker is reachable. Ending the workspace stops its running preview. A [saved artifact](https://usefiretower.com/docs/artifacts) is a separate output.