Case 2 — Add Tool Use to an LLM Agent

# Case 2 — Add Tool Use to an LLM Agent > *"Build a support agent that can look up order status, check refund eligibility, create tickets, and escalate to humans. Use Claude's tool-use feature."* --- ## Step 1 — Define the tools ```python tools = [ { "name": "get_order_status", "description": "Look up the current status, tracking info, and estimated delivery of a customer's order. Use when the customer asks about their order, shipping, delivery, or tracking. Requires order_id.", "input_schema": { "type": "object", "properties": { "order_id": {"type": "string", "description": "Order ID, e.g., '12345'"} }, "required": ["order_id"] } }, { "name": "check_refund_eligibility", "description": "Check if an order is eligible for refund. Returns eligibility status and reasoning. Use BEFORE promising a refund.", "input_schema": { "type": "object", "properties": { "order_id": {"type": "string"} }, "required": ["order_id"] } }, { "name": "initiate_refund", "description": "Initiate a refund for an eligible order. Only call after check_refund_eligibility returns eligible=true. Returns the refund ID and ETA.", "input_schema": { "type": "object", "properties": { "order_id": {"type": "string"}, "reason": {"type": "string", "description": "Customer's stated reason for refund"} }, "required": ["order_id", "reason"] } }, { "name": "create_support_ticket", "description": "Create a support ticket for issues that need human attention. Use when: customer expresses frustration, request is outside scope, or you're unsure how to proceed.", "input_schema": { "type": "object", "properties": { "customer_id": {"type": "string"}, "category": {"type": "string", "enum": ["complaint", "feature_request", "billing", "technical", "other"]}, "summary": {"type": "string"}, "priority": {"type": "string", "enum": ["low", "medium", "high", "urgent"]} }, "required": ["customer_id", "category", "summary", "priority"] } }, ] ``` Notice: descriptions explicitly state WHEN to call each tool, and constraints (e.g., "only call initiate_refund after eligibility check"). ## Step 2 — Implement the tools ```python def get_order_status(order_id): order = db.query("SELECT * FROM orders WHERE id = ?", order_id) if not order: return {"error": "Order not found"} return { "order_id": order.id, "status": order.status, "carrier": order.carrier, "tracking_number": order.tracking, "estimated_delivery": order.eta.isoformat(), "placed_at": order.created_at.isoformat(), } def check_refund_eligibility(order_id): order = db.query("SELECT * FROM orders WHERE id = ?", order_id) if not order: return {"eligible": False, "reason": "Order not found"} days_since = (datetime.utcnow() - order.created_at).days if days_since > 30: return {"eligible": False, "reason": f"Order is {days_since} days old; refund window is 30 days"} if order.status == "delivered" and order.delivered_at: days_since_delivery = (datetime.utcnow() - order.delivered_at).days if days_since_delivery > 30: return {"eligible": False, "reason": f"Delivered {days_since_delivery} days ago; return window expired"} return {"eligible": True, "reason": "Within refund window"} def initiate_refund(order_id, reason): eligibility = check_refund_eligibility(order_id) if not eligibility["eligible"]: return {"success": False, "error": eligibility["reason"]} refund = refund_service.create(order_id=order_id, reason=reason) return { "success": True, "refund_id": refund.id, "eta_days": 3, } def create_support_ticket(customer_id, category, summary, priority): ticket = support_service.create_ticket( customer_id=customer_id, category=category, summary=summary, priority=priority, ) return {"ticket_id": ticket.id, "created": True} TOOL_REGISTRY = { "get_order_status": get_order_status, "check_refund_eligibility": check_refund_eligibility, "initiate_refund": initiate_refund, "create_support_ticket": create_support_ticket, } ``` ## Step 3 — The agent loop ```python import anthropic claude = anthropic.Anthropic() SYSTEM_PROMPT = '''You are a customer support agent for Acme. You can look up orders, check refund eligibility, initiate refunds, and create support tickets. Guidelines: - Be empathetic and concise. - ALWAYS check refund eligibility before promising a refund. - If unsure, create a support ticket and t