ContentBlock and derived types, and ResourceContents and derived types at a minimum. Additionally, any other types that appear as part of the public surface and don't have good default debugger representations.

ToString should only be overidden if the type represents text data.

DebuggerDisplay should be added for types that can't provide a meaningful ToString overload and should give a useful representation of the type. Have a look at https://github.com/search?q=repo%3Adotnet%2Fextensions+path%3A%2F%5Esrc%5C%2FLibraries%5C%2FMicrosoft%5C.Extensions%5C.AI%5C.Abstractions%5C%2F%2F+DebuggerDisplay&type=code for inspiration.

For example https://github.com/dotnet/extensions/blob/4a49fcf893bc3e753a201c35b3c0bb4e264d1297/src/Libraries/Microsoft.Extensions.AI.Abstractions/Contents/DataContent.cs#L237