Adds key-level annotations to a schema field. This is the pipeable (curried) counterpart of the .annotateKey method.

Details

Key annotations apply to a field's position inside a Struct or Tuple rather than to the field's value type. They can carry a messageMissingKey to customise the error shown when the field is absent, as well as standard documentation fields such as title, description, and examples.

Example (Customizing the missing-key message for a required field)

import { Schema } from "effect"

const schema = Schema.Struct({
  username: Schema.String.pipe(
    Schema.annotateKey({
      description: "The username used to log in",
      messageMissingKey: "Username is required"
    })
  )
})