There is another option for anyone who can write a reasonable parser, select the start of an API or similar function in your own assembler code then scan the function call from its start to its end. Count the arguments then refer to a fast access list to get the argument count.
A relatively straight forward tool to make and if you had it set up in the editor of your choice, you would place the cursor on the function name and just press a key and it would come back as an argument count plus any other information you wanted to attach to the function call.
Making the fast lookup list would take a lot of work but it could be done.