Thank you for contacting Rider support. Apologies for keeping you so long without an answer.
When you navigate into built-in types, such as String, Rider downloads a file from official dotnet repository and showw you its content.
I compared String.java and String.cs and saw that java file indeed contains much more documentation. However, relatively little documentation in String.cs is not an issue on Rider side. Rider only shows documentation that exists in official repository. (String.cs on GitHub).
After navigating into String.cs I see the following picture. Is it the same for you? If it doesn't match to what you see, please let me know. I would appreciate it if you could elaborate on the issue and share a screenshot that demonstrates it.
Hello,
Thank you for contacting Rider support.
Apologies for keeping you so long without an answer.
When you navigate into built-in types, such as String, Rider downloads a file from official dotnet repository and showw you its content.
I compared String.java and String.cs and saw that java file indeed contains much more documentation. However, relatively little documentation in String.cs is not an issue on Rider side. Rider only shows documentation that exists in official repository. (String.cs on GitHub).
After navigating into String.cs I see the following picture. Is it the same for you?

If it doesn't match to what you see, please let me know. I would appreciate it if you could elaborate on the issue and share a screenshot that demonstrates it.
Have a nice day!