Are there any tools to download "variable information list" file from AA? Or do we always have to check the codes in the atmx files to review the variable information ? Variable information means code row the variables are used in ,and the variable mapping from task to task.
To a degree it is possible to do what you are asking within AA. If you add a "Send Email" command to your script and then in the attachment section select 'attach all variables', which can be done by pressing the $ symbol.
When run it will email you with an attachment, which has a snapshot of all user and system variables at the time it was run, similar to what you can do with emails in the "Begin Error Handler" command. If you put it at the top it should show you the variables as per the script starting, if you add it at the end though it could be changed by any variable operations you have included in your script.
When documenting an automation I usually copy all the variables from all the scripts created into a new script with the method above, so i can get a list of all the variables used.
As de.Vina has already pointed out though, it is not best practice to hard code values into variables and it should be done via a configuration file.