Such tools usually work via an Entra ID integrated app, so your best course is to block said app. Go to the Entra ID portal > Applications > Enterprise applications and search for the app. You might have to adjust the filters on top for all entries to appear. Once you find the corresponding application, click on it, go to Properties and toggle the Enabled for users to sign-in? control. Alternatively, if you want to make it available to select users only, toggle the Assignment required? control and assign users under Users and Groups.
If you need more details, refer to this article: https://learn.microsoft.com/en-us/entra/identity/enterprise-apps/disable-user-sign-in-portal?pivots=portal