See attached image, with all details. WDL also available at http://gdac.broadinstitute.org/runs/tmp/echo.wdl)
FWIW, wdltool does not indicate anything is wrong with the WDL. My local WDLtool version is 0.8, with MD5 hash
786d376141910f2176fb38dde5891b36 /Users/mnoble/src/gdac-firecloud/bin/wdltool.jar