How do I write comments about class library methods, properties, and so on, before calling DLL files elsewhere, smart hints appear in the code?

my intention is to tidy up the previous code library, to my own code to increase the reusability. After a while, you might forget about what the code was written about, or someone else would look at your code,

Increase the understanding of the consideration, decide to add comments. (as if the statement did not pass:) but found that the DLL file is referenced in other locations and cannot get the comments that were added earlier.

Workaround, just one step: under the project, Select the XML document file in the build . Simple and practical skills get hands !

How do I write comments about class library methods, properties, and so on, before calling DLL files elsewhere, smart hints appear in the code?