Ivan,


<tool name="UCSC Main" id="ucsc_table_direct1" tool_type="data_source">
   <description>table browser</description>
   <command interpreter="python">
       #if $__user_email__ == ""
       <display>You are not authorized to use this tool</display>
       #else
       data_source.py $output $__app__.config.output_size_limit
       #end if
</command>



... and I got the error below, which seems connected to
the cheetah syntax. Any idea of what I'm doing wrong?

As is tradition in python, you need to put semi-colons after conditionals. E.g.

--
#if $__user_email__ == "":
       <display>You are not authorized to use this tool</display>
#else:
       data_source.py $output $__app__.config.output_size_limit
#end if
--


J.