web api description filter

ApiOperationDescriptionAttribute.cs

    public class ApiOperationDescriptionAttribute : Attribute
    {
        public string Description { get; set; }
        public ApiOperationDescriptionAttribute(string description)
        {
            Description = description;
        }   
    }
    
    public class LookupOperationFilter : IOperationFilter
    {
        public void Apply(Operation operation, SchemaRegistry schemaRegistry, System.Web.Http.Description.ApiDescription apiDescription)
        {
            var attribs = apiDescription.ActionDescriptor.GetCustomAttributes<ApiOperationDescriptionAttribute>();
            var desc = attribs.FirstOrDefault();
            if (desc != null)
            {
                operation.description = desc.Description;
            }
        }
    }

Startup.cs

public class Startup
{
        public void Configuration(IAppBuilder app)
        {
            
            var config = new HttpConfiguration();
            config.EnableSwagger(c =>
            {
                c.SingleApiVersion("v1", "My API");
                c.DescribeAllEnumsAsStrings();
                c.OperationFilter<LookupOperationFilter>();
            });
            WebApiConfig.Register(config);
            ...
        }
  }