Definition
Arguments
Overview
@specifiedBy is a built-in GraphQL directive defined in the
GraphQL specification.
It provides a machine-readable link between a custom scalar type and the document
that describes its serialization,
coercion,
and validation rules.
The URL is exposed through introspection via the specifiedByURL field on scalar types.
Tools and clients can use this to generate documentation or validate scalar values.
This directive must not be applied to built-in scalar types
(String, Int, Float, Boolean, ID).
Examples
Linking a scalar to an RFC
Linking to the GraphQL Scalars registry
Custom format specification
Federation behavior
In a federated graph, every subgraph that defines the same custom scalar should use the same@specifiedBy URL.
Cosmo preserves the directive through composition so that introspection on the federated schema
returns the specifiedByURL for each annotated scalar.
The router does not perform any runtime validation based on this directive.
It is purely a schema metadata directive for documentation and tooling.