it's not completed yet:
http://dev.processing.org/bugs/show_bug.cgi?id=124

so there's no means to dynamically load them or a set api. the show() thing is the current method, but it also requires that the code be added to the p5 source by hand. in the end there will be some sort of setup() method that runs as the tool is loaded, a show() method (probably called something else because Frame.show() is deprecated in 1.5.. yay!) and perhaps a hide() method that'll shut things down. if you think along that model then you should be ok for it working once i have a chance to finish the menu.

*do not* put the code in package processing.app. that's only for stuff from teh actual p5 distribution.

just a thought. i think it would be a good idea to categorize the tools(*) ( online, search, format, ...). that way the menu could be structured and less crowded once people start writing their own tools ...

best,
F

(*)
for example: let people use one of / choose from a predefined set of types, like:
class myTool {
 int tool_cat = TOOL_ONLINE;
}