Attributes Overview

Attributes in BAML provide additional metadata or behavior to fields and types.

Field-Level Attributes

Applied to individual fields within a class or enum.

Attribute	Description
`@alias`	Renames field for LLM understanding
`@description`	Adds context to a field
`@skip`	Excludes from prompts/parsing
`@assert`	Strict validation (raises exception)
`@check`	Non-exception validation

class MyClass {
    property1 string @alias("name") @description("The name of the object")
    age int? @check(positive, {{ this > 0 }})
}

Applied to entire classes or enums, affecting all fields/values.

Attribute	Description
`@@dynamic`	Allows runtime field modification
`@@assert`	Block-level strict validation
`@@check`	Block-level non-exception validation

class MyClass {
    property1 string
    property2 int?

    @@dynamic  // allows adding fields at runtime
}