Unable to fetch annotated vales from JAR File

annoted class shown below present inside MySample project

@Description(name = "foo", description = "bar")
public class Test {

    //////

}

Fetching vales from jar in below code

File file  = new File("MySample.jar");
    URL url = file.toURL();  
    URL[] urls = new URL[]{url};

    ClassLoader cl = new URLClassLoader(urls);
    Class cls = cl.loadClass("com.example.Test");
    Description annotations = cls.getClass().getAnnotation(Description.class);

    // annotations instance is null

Because of annotations instance null i am not able to fetch vales.

Does any one have idea how to solve this problem or any other alternatives ?