I added a docblock like this:

• Creates a object containing all evidence pertaining to the portfolio with the given id
  *
• @param string $url the url of the web site that will be downloaded
• @param string $savedir the name of the directory to save the retrieved site in

(extra spaces after 'string' on both lines so that all the $ signs line up - there are a load more parameters)

and got an error like this:

44 | WARNING | The comments for parameters $url (1) and $savedir (2) do not

Which conflicts with advice here where the $ signs line up: http://docs.moodle.org/en/Development:Coding_style#Functions