The desk agent and its tools

The shop desk is an Agent that answers an order question by calling a tool, the first piece of the support desk you finish in this part.

Last updated: 28 Sep, 2026 · openai-agents 0.22.3

Runner and the RunResult object arrived in the lesson on Runner and the RunResult object, and the tool decorator arrived in function_tool: a function the model can call. Here they meet: one agent, one tool, one order question, run against the ShopModel stand-in so no API key is needed.

The pieces, and where each came from

The lookup tool

A tool is a plain function with the @function_tool decorator. Its docstring tells the model what it does.

@function_tool
def lookup_order(order_id: str) -> str:
    "Look up an order by its id."
    return f"Order {order_id}: shipped on 3 March, arriving 7 March."

The desk agent

The desk is an Agent that carries the tool in its tools list and uses the stand-in model.

desk = Agent(
    name="Shop desk",
    instructions="Help shoppers with their orders.",
    tools=[lookup_order],   # the desk may call this tool
    model=ShopModel(),      # the stand-in, no API key
)

Asking one order question

Runner.run_sync drives the run and hands back a result; final_output is the answer.

result = Runner.run_sync(desk, "Where is my order A17?")
print(result.final_output)

The desk answering an order question

The whole desk in one file, ready to run against the stand-in.

from agents import Agent, Runner, function_tool, set_tracing_disabled
from shop_model import ShopModel
set_tracing_disabled(True)

@function_tool
def lookup_order(order_id: str) -> str:
    "Look up an order by its id."
    return f"Order {order_id}: shipped on 3 March, arriving 7 March."

desk = Agent(
    name="Shop desk",
    instructions="Help shoppers with their orders.",
    tools=[lookup_order],
    model=ShopModel(),
)
result = Runner.run_sync(desk, "Where is my order A17?")
print(result.final_output)

What the run produced

• The stand-in saw the word order, so it asked to call lookup_order with id A17 instead of answering straight away.
• The runner ran the tool and fed its return value back to the model.
• The final answer is the tool's line, because the model turns a tool result into the reply.

A desk with a tool vs a desk with none

When the desk needs a tool

• Any answer that depends on live data, an order status, a balance, a booking, belongs in a tool, not in the instructions.
• The desk stays small: the model decides, the tool fetches, the model replies.

Related

• Previous: Capping a run with max_turns
• Next: A refund specialist by handoff
• Reference: Tools