Annotating Agent Methods (Rust)

Overview

Golem agents can annotate methods with #[prompt] and #[description] attributes. These provide metadata for AI/LLM tool discovery — agents with annotated methods can be used as tools by LLM-based systems.

Annotations

• #[prompt("...")] — A short instruction telling an LLM when to call this method
• #[description("...")] — A longer explanation of what the method does, its parameters, and return value

Usage

use golem_rust::{agent_definition, agent_implementation, prompt, description};

#[agent_definition]
pub trait InventoryAgent {
    fn new(warehouse_id: String) -> Self;

    #[prompt("Look up the current stock level for a product")]
    #[description("Returns the number of units in stock for the given product SKU. Returns 0 if the product is not found.")]
    fn check_stock(&self, sku: String) -> u32;

    #[prompt("Add units of a product to inventory")]
    #[description("Increases the stock count for the given SKU by the specified amount. Returns the new total.")]
    fn restock(&mut self, sku: String, quantity: u32) -> u32;

    #[prompt("Remove units of a product from inventory")]
    #[description("Decreases the stock count for the given SKU. Returns err if insufficient stock.")]
    fn pick(&mut self, sku: String, quantity: u32) -> Result<u32, String>;
}

Guidelines

• #[prompt] should be a natural-language instruction an LLM can match against a user request
• #[description] should document behavior, edge cases, and expected inputs/outputs
• Both annotations are optional — omit them for internal methods not intended for LLM discovery
• Annotations have no effect on runtime behavior; they are purely metadata