Designing Simple Tool Interfaces › Chaining Tools

Sometimes answering a question requires using multiple tools in sequence. Consider this request:

User: What should I wear for my meeting tomorrow in Chicago?

To answer this, the agent needs to:

1. Check the calendar to find when the meeting is
2. Get the weather forecast for Chicago at that time
3. Reason about appropriate attire based on the weather and meeting type

This is called tool chaining. The output of one tool becomes input to the next:

Step 1: check_calendar(date="tomorrow")
→ Result: Meeting at 2 PM, type: "client presentation"

Step 2: get_forecast(city="Chicago", date="tomorrow", time="2 PM")
→ Result: 45°F, rainy

Step 3: Agent reasons about the results
→ Response: "Your client presentation in Chicago tomorrow is at 2 PM. 
   It will be 45°F and rainy, so I'd recommend business attire with 
   a coat and umbrella."

The agent orchestrates this sequence, using the output from each tool to inform what to do next. This is where the agent's reasoning capabilities (from Chapter 4) combine with its tool use abilities to handle complex, multi-step tasks.