commenting callback functions

Usually you will just write an invocation of the function with speaking names:

/* 
 * @param {String} input: the text
 * @param {Function} callback(output, hasChanged): called after calculation
 */

Or, if the parameters need explanation, you can use a multiline description:

/* 
 * @param {String} input: the text
 * @param {Function} callback(result, change)
 *         the function that is called after calculation
 *         result {String}: the output of the computation
 *         change {Boolean}: whether a change has occurred
 */

I don't know about any conventions for this. I would just use:

@param {Function} Called on success with the response (string) as the first param and the status code (int) as the second

I am aware it's quite verbose though.

Another option would be doing it like this (similar to how jQuery does it, not in code that I am aware of, but in their documentation)

@param {Function} onSuccess(response, statusCode)

Here's an example http://api.jquery.com/jQuery.ajax/ It's different of course since this is an options object and the documentation has a different structure than inline documentation. But look at the callbacks and you will see the similarity.

It's also a much better idea to use callback(response, statusCode) than callback(string, int) for clarity. If you have to choose one that is. Meaning before type.