FF Tool has been blocked for your protection.

Why was it blocked?
These are a set of malicious add-ons that block the add-ons manager tab from opening so they can't be uninstalled.
What does this mean?

The problematic add-on or plugin will be automatically disabled and no longer usable.

When Mozilla becomes aware of add-ons, plugins, or other third-party software that seriously compromises Firefox security, stability, or performance and meets certain criteria, the software may be blocked from general use. For more information, please read this support article.