add tool use example

examples/tool_use.py

@@ -0,0 +1,137 @@
+#!/usr/bin/env -S uv run python
+
+"""Example demonstrating tool use (function calling) with the Anthropic SDK.
+
+This example shows how to:
+1. Define tools with JSON Schema input descriptions
+2. Send a message that triggers tool use
+3. Process the tool call and return results
+4. Get Claude's final response incorporating the tool results
+
+Usage:
+    export ANTHROPIC_API_KEY="your-api-key"
+    python examples/tool_use.py
+"""
+
+import json
+
+from anthropic import Anthropic
+
+client = Anthropic()
+
+# Define tools that Claude can use
+tools = [
+    {
+        "name": "get_weather",
+        "description": "Get the current weather in a given location.",
+        "input_schema": {
+            "type": "object",
+            "properties": {
+                "location": {
+                    "type": "string",
+                    "description": "The city and country, e.g. 'London, UK'",
+                },
+                "unit": {
+                    "type": "string",
+                    "enum": ["celsius", "fahrenheit"],
+                    "description": "Temperature unit (default: celsius)",
+                },
+            },
+            "required": ["location"],
+        },
+    }
+]
+
+
+def get_weather(location: str, unit: str = "celsius") -> dict:
+    """Simulate a weather API call.
+
+    In a real application, this would call an actual weather API.
+    """
+    # Simulated weather data
+    weather_data = {
+        "London, UK": {"temp": 12, "condition": "Cloudy", "humidity": 78},
+        "New York, US": {"temp": 22, "condition": "Sunny", "humidity": 45},
+        "Tokyo, JP": {"temp": 18, "condition": "Partly cloudy", "humidity": 60},
+    }
+
+    data = weather_data.get(location, {"temp": 20, "condition": "Unknown", "humidity": 50})
+
+    if unit == "fahrenheit":
+        data["temp"] = round(data["temp"] * 9 / 5 + 32)
+
+    return {
+        "location": location,
+        "temperature": data["temp"],
+        "unit": unit,
+        "condition": data["condition"],
+        "humidity": data["humidity"],
+    }
+
+
+def process_tool_call(tool_name: str, tool_input: dict) -> str:
+    """Route tool calls to the appropriate function."""
+    if tool_name == "get_weather":
+        result = get_weather(**tool_input)
+        return json.dumps(result)
+
+    return json.dumps({"error": f"Unknown tool: {tool_name}"})
+
+
+def main() -> None:
+    print("=== Tool Use Example ===\n")
+
+    # Step 1: Send a message that will trigger tool use
+    user_message = "What's the weather like in London and Tokyo?"
+    print(f"User: {user_message}\n")
+
+    messages = [{"role": "user", "content": user_message}]
+
+    # Step 2: Get Claude's response (may include tool use requests)
+    response = client.messages.create(
+        model="claude-sonnet-4-5-20250929",
+        max_tokens=1024,
+        tools=tools,
+        messages=messages,
+    )
+
+    # Step 3: Process tool calls in a loop until Claude gives a final response
+    while response.stop_reason == "tool_use":
+        # Collect all tool use blocks from the response
+        tool_results = []
+        for block in response.content:
+            if block.type == "tool_use":
+                print(f"Tool call: {block.name}({json.dumps(block.input)})")
+                result = process_tool_call(block.name, block.input)
+                print(f"Tool result: {result}\n")
+
+                tool_results.append(
+                    {
+                        "type": "tool_result",
+                        "tool_use_id": block.id,
+                        "content": result,
+                    }
+                )
+
+        # Step 4: Send tool results back to Claude
+        messages = [
+            *messages,
+            {"role": "assistant", "content": response.content},
+            {"role": "user", "content": tool_results},
+        ]
+
+        response = client.messages.create(
+            model="claude-sonnet-4-5-20250929",
+            max_tokens=1024,
+            tools=tools,
+            messages=messages,
+        )
+
+    # Step 5: Print Claude's final response
+    for block in response.content:
+        if hasattr(block, "text"):
+            print(f"Claude: {block.text}")
+
+
+if __name__ == "__main__":
+    main()