This really needs to be documented better in the Help file.
When executing commands from the 'command line' (editbox), the / prefix is required. (you shouldn't use / in actual scripts) Using only a single / will execute the command without sending it through mIRC's Script Parcer to evaluate %variables and $identifiers and other formatting, including |.
To evaluate these things, you must use the // prefix in the 'command line' (editbox).
//describe #channel1 EXAMPLE | describe #channel2 EXAMPLE2
Other prefixes to know about are . to Silence or make the command Quiet (no display output), and ! to prevent an Alias of similar name from superseding an internal mIRC command.
All prefixes can be used in combination with one-another.
- Raccoon