A visual demo.  Nothing fancy, more for the record.

1 Begin by creating a toolbox

2  Specify a 'New' script to create a script in the toolbox

3  Now start filling out the dialog's General parameters.

4 The actual Parameters section needs to be created to include Label, Name, Data Type, whether it is

    required,  optional or derived and whether it is an input or output parameter.

5  Kind of obvious what needs to be done... elapsed time so far, 2 minutes.

Some get a bit more complicated

6  You can fill out tool validation if you want.  I personally don't bother unless someone is paying.

7  Time for the help stuff...this is important though

8  Yes... the less than obvious save button will make things good. 

    You can include all kinds of stuff, like images etc.

    Sidebar help

9 Ready to roll.

10  Oh yes... the handy little 'i' symbol shows the tool help if you just need a quick tip on the input parameters.

Total elapsed time from start to finish, less than 5 minutes.

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Extras

Multivalue parameters are possible

Store you toolbox, main script and helper script together

You can embed your script in the toolbox should you want to...just don't forget your password and keep a non-embedded version just in case.