Could I, for example, upload some txt / pdf / docx files?
You can do this by enabling tools on the agent. For instance, if you have a set of RFP documents and you store them in the Ontology as a “RFP” object, you can then give an agent the ability to query “RFP”. With an instruction such as “reference the RFP ontology for common patterns” you can have the agent understand your old documents. For search and retrieve you will want to vectorize your documents first.
But this is only possible for AIP Agents, not for AIP Assist Agents.
Sorry for that! This document does a nice job showing what you can do, but currently this is only supported for Notepad docs and Markdown Format within your documentation repository in Code Repositories. You can always re-format your other docs as markdown and store them in your code repo, for now.