get https://app.asana.com/api/1.0/projects//custom_field_settings
Returns a list of all of the custom fields settings on a project, in compact form. Note that, as in all queries to collections which return compact representation, opt_fields can be used to include more data than is returned in the compact representation. See the documentation for input/output options for more information.
Customizing the response
Requests to this endpoint return "compact" custom field setting objects (schema) by default. To include more fields in the response, see input/output options.