Mobile Tools detects mobile and iPad, not Android tablet
Have you looked at ThemeKey? It has OS based redirection rules. Here is a quote about it (from the module's project page):

... allows you to define simple or sophisticated theme-switching rules which allow automatic selection of a theme depending on current path, taxonomy terms, language, node-type, and many, many other properties. It can also be easily extended to support additional properties exposed by other modules. In combination with Drupal's theme inheritance you can easily achieve features like:

individually-styled channels
a front-page / &quot;splash&quot; screen
a date/time-selected Christmas theme
mobile themes for different auto-detected mobile devices
special themes for &quot;limited&quot; or &quot;old&quot; browsers
content, user, or role -specific themes
indicating your environment (production, staging, testing, sandbox, … )
testing your redesign safely on a live server