Attributes

All attributes live in the Rivet namespace (Rivet.Attributes package). They are read by Roslyn at generation time; none of them changes runtime behaviour, with one exception — [RivetConstraints] is a ValidationAttribute and is enforced by validating hosts at runtime.

Discovery

Attribute	Target	Effect
[RivetContract]	static class	Marks a contract class; its static readonly RouteDefinition fields become operations.
[RivetClient]	class	Marks a controller class; all public methods with HTTP attributes ([HttpGet], ...) become operations.
[RivetEndpoint]	method	Marks an individual controller/minimal-API method as an operation.
[RivetType]	class, enum	Forces a type to be walked into components/schemas even if no endpoint references it.

Schema metadata

Attribute	Target	Effect in the spec
[RivetDescription("text")]	property, class	description
[RivetExample("json")]	property	examples: [value] (3.1 keyword; value parsed as a JSON literal)
[RivetDefault("json")]	property	default (JSON literal)
[RivetOptional]	property	Removes the property from required
[RivetReadOnly] / [RivetWriteOnly]	property	readOnly: true / writeOnly: true
[RivetFormat("fmt")]	property	format — for custom formats (uri-template, currency, ...) with no dedicated C# type; takes precedence over formats inferred from DataAnnotations
[RivetConstraints(...)]	property	exclusiveMinimum, exclusiveMaximum, multipleOf, minItems, maxItems, uniqueItems — constraints DataAnnotations cannot express. Also a ValidationAttribute: enforced at runtime under validating hosts ([ApiController] model validation, Validator.TryValidateObject); null values pass — pair with [Required]. See Runtime validation
[RivetHeader("Wire-Name")]	property	Marks a contract input-record property as a request header parameter (in: header, original casing preserved; without a name the property name is the header name). The property never enters the JSON schema. Spec-only — header binding stays the host's job. Accept/Content-Type/Authorization are rejected by the emitter (RIV2009).

Operation metadata

Attribute	Target	Effect
[RivetRequestExample(json, ...)]	method, contract field	Request body example (optionally named, per media type, or referencing a component example)
[RivetResponseExample(status, json, ...)]	method, contract field	Response example for a status code
[ProducesFile]	contract field	Marks the endpoint as returning a file download

Standard attributes Rivet also reads

• System.ComponentModel.DataAnnotations: [Required], [Range], [MinLength], [MaxLength], [StringLength], [RegularExpression], [EmailAddress], [Url] → JSON Schema constraints and formats.
• System.Text.Json: [JsonPropertyName("x")] overrides the camelCased property name.
• ASP.NET: [Route], [HttpGet]/[HttpPost]/..., [ProducesResponseType], [FromBody]/[FromQuery]/[FromForm]/[FromHeader]/... drive operation shape on controller endpoints. [FromHeader(Name = "X-Api-Key")] maps to an in: header parameter with the attribute's casing (P2 wave 5; previously excluded with the now-retired RIV1005).
• [Obsolete] → deprecated: true.

None of the constraint metadata is validated by Rivet at runtime — see Runtime Validation.