I am using JSON.NET to generate JSON Schema from c# object class. But I was unable to add any other json schema attributes e.g. maxLength, pattern(regex to validate email),
Json.NET Schema now has much improved schema generation support.
You can annotate properties with .NET's Data Annotation attributes to specify information like minimum, maximum, minLength, maxLength and more on a schema.
There is also JSchemaGenerationProvider that lets you take complete control when generating a schema for a type.
More details here: http://www.newtonsoft.com/jsonschema/help/html/GeneratingSchemas.htm