C# OData CsdlWriter always generates empty XML

Question

I'm trying to generate CSDL xml suitable for an OData $metadata endpoint, however I am not using Entity Framework or anything similar. Currently I just want to generate the $metadata XML document for a small set of ~3 classes...

My code looks like the following...

var modelBuilder = new ODataConventionModelBuilder();

modelBuilder.AddEntity(typeof(Member));

var model = modelBuilder.GetEdmModel();

IEnumerable<EdmError> errors;
CsdlWriter.TryWriteCsdl(model, 
    XmlWriter.Create(HttpContext.Current.Server.MapPath(...),
    out errors);

...however, the output XML is always empty. I've tried modelBuilder.Entity<>, modelBuilder.AddEntity(type), modelBuilder.EntitySet<> etc to no avail.

The Member class is simply public getters and setters - do I need attributes? What is the best way to generate $metadata XML if you're not hosting it or using EntityFramework?

Apologies if this is a basic question, but I can't find any documentation for this that doesn't assume you're using EF or hosting from an OData endpoint, and I'm doing neither of these things.