Create an assignment (require one file) with the PDF annotation feedback tool enabled, see ( https://docs.moodle.org/30/en/Using_Assignment#Annotating_PDF_files for the required settings) As a student submit the assignment (submit a pdf file), as a teacher review the submission adding some annotations in the pdf file. As admin, enable "Mobile services": Plugins ► Web Services ► Mobile Create a Token for the student Click on Site administration ► Plugins ► Web services ► Manage tokens Next, you can do a CURL REST call simulating a WS client with one of the student users. You need to replace the wstoken, assignid (with the instance id, not the cmid) and the URL of your moodle instance curl 'http://localhost/m/stable_master/webservice/rest/server.php?moodlewsrestformat=json' --data 'assignid=32&wsfunction=mod_assign_get_submission_status&wstoken=ffbe3a3002f235bf9d01fd9369e10b66' | python -m "json.tool" Now, check that in the response you see among other data listed the pdf annotated file, you can download that file appending ?token=USERTOKEN to the file path, and check that the file is downloaded correctly For the older Moodle versions the only way you can test it is running the unit tests