come on help files and such yadayada ;) 2 ways:

1.) open the shader file in a text editor and look at the first few lines. All of them are in:

C:Program FilesCycling '74MaxMSP 4.6Cycling '74jitter-shaders (windows something else similar in mac)

2.) open the help file on jit.gl.slab and the html help

quote:

getparamlist Sends the names of all the internal jit.gl.shader object shader parameters out the right-most outlet.

getparamtype [name (symbol)] Sends the name of the datatype for the indicated shader parameter for the internal jit.gl.shader object out the right-most outlet.