Well, first of all, you need to rename the xml from Description3.xml to Description.xml
Second of all, even if we get this thing to be recognized, I'm not sure it will work. According to the help documenation, the TestedApps object is not available in script extensions so your call in openApp.js to the TestedApps object will not work.
Finally, there's a misspelling in your xml. The last "Description" tag had a misspelling in the close tag.
<Description>This extension opens App</Decription>
Correct that and it should be recognized. However, I think you'll find that you'll need to do some more work with your js file itself.