The question is - is that function relevant and understandable by whoever is going to be doing your card sort? I think your example would, in theory, make a fine card. Here's some words from a real expert:
Donna Spencer wrote a great book titled Card Sorting, and she's got a precursor article that contains this:
Granularity and sampling content.
Content selected for the cards can be individual pages, functionality, small groups of pages, or whole sections of the site. Be consistent with your chosen granularity—participants will find it difficult to group content at different levels of granularity.
If you choose to use small groups of pages or sections of the site, ensure that the groups are of items that belong together. For example, don’t include a grouping of “media releases,” as this may not suit users and their tasks (they may prefer individual media releases to be grouped with other pages of similar topic.). Instead, include some individual media releases and see what participants do with them.
The content for the card sort should be representative of the site (or the part of site that you are investigating). It is important to ensure that the content has enough similarity to allow groupings to be formed. If the content chosen is too varied, participants will not be able to create natural groupings.