Embabel Agent Documentation/com.embabel.agent.api.annotation/LlmTool

LlmTool

@Target(allowedTargets = [AnnotationTarget.FUNCTION])

annotation class LlmTool(val description: String = "", val name: String = "", val returnDirect: Boolean = false, val category: String = "", val metadata: Array<LlmTool.Meta> = [])

Marks a method as a tool that can be invoked by an LLM. Use with com.embabel.agent.api.tool.Tool.Companion.fromInstance or com.embabel.agent.api.tool.Tool.Companion.fromMethod to create Tool instances.

Types

@Target(allowedTargets = [])

annotation class Meta(val key: String, val value: String)

A key-value metadata entry for use in LlmTool.metadata.

@Target(allowedTargets = [AnnotationTarget.VALUE_PARAMETER])

annotation class Param(val description: String, val required: Boolean = true)

Describes a tool parameter. Apply to method parameters. Parameters don't need to be annotated: If they are, the purpose is to provide description and required information.

Properties

val category: String

Optional category for use with MatryoshkaTools. When the containing class has @MatryoshkaTools, tools with the same category are grouped together and exposed when that category is selected. Leave empty for tools that should always be exposed.

val description: String

Description of what the tool does. Used by LLM to decide when to call it.

val metadata: Array<LlmTool.Meta>

Application-level metadata entries merged into com.embabel.agent.api.tool.Tool.Definition.metadata. Used for routing, categorization, feature flags, etc. — not sent to the LLM.

val name: String

Tool name. Defaults to method name if empty.

val returnDirect: Boolean = false

Whether to return the result directly without further LLM processing.