Permissions
This page explains what permissions Multi-Account Containers asks upon installation and why it needs them.
Required to provide the feature that enables automatic reopening of websites in target containers by selecting "Always open in" in the toolbar popup. In order to do that, it is necessary to be able to intercept and potentially cancel every request inside the browser. This is the all_urls permission in combination with the webRequest and webRequestBlocking permissions.
Required to remove entries from the history generated from Multi-Account Containers when showing the Confirm Page - which lets you decide in which container you want the website to open in if the website is assigned using "Always open in". This is the history permission.
Required to access the tabs URL, which is also needed to provide automatic reopening of websites in the correct target container in cases where the currently loaded URL in the tab is relevant to decide whether to stay in a container or open a new one. This is the tabs permission.
Required to provide interoperability with other container Add-ons by checking if they have the required permissions. This is the management permission.
More required and used permissions included in the Add-on that don't show up as special text when installing the Add-on are:
Required to add entries to context menu entry when right clicking.
Required to use the container feature itself, which is natively available in Firefox with this permission.
Required to manage tabs based on the "cookieStoreId", which is the internal way of handling tabs in combination with the container feature.
Required to store and read preferences/options and data needed to provide functionality.
Required to configure custom proxy settings per container.
Required to interact with the Mozilla VPN client if installed. This allows having custom VPN locations per container. The communication happens via native messaging API.
This allows you to open a bookmark or folder of bookmarks in a Container.