iRule to TCL Conversion Script: https://support.f5.com/csp/article/K15650046

take the code between the when brackets and add a tcl shebang I guess

eg

when HTTP_REQUEST {
# some tcl code here
}

changes to:

#!/usr/bin/tclsh
#some tcl code here

Though i guess it is mainly looking for expr. I used VS code and the irule plugin. I have also used regex to statically check.