Clara cannot see attachments, see that there is an attachment on a thread, share attachments via email or calendar invite, or access data in a hyperlink (with the exception of scheduling tool links). This is for both your security and privacy, as well as for Clara's security.
Best practice is to copy relevant information that Clara needs and paste it as part of the email text, or provide text-based guidance.
For example: "Tell Joe to check our recruiting website for that info."
Another example: If you are attending a several-day offsite and would like Clara to add events to your calendar, copy/paste the text of the agenda into an email to Clara, with a limit of 3 events per email request.