feat(callback_handler): optional verbose output for PrintingCallbackHandler (#1211)

Make the verbose description and counting of tool use optional in PrintingCallbackHandler.
---------

Co-authored-by: Dean Schmigelski <[email protected]>

Author: marcbrooker

src/strands/handlers/callback_handler.py

@@ -7,10 +7,15 @@
 class PrintingCallbackHandler:
     """Handler for streaming text output and tool invocations to stdout."""
 
-    def __init__(self) -> None:
-        """Initialize handler."""
+    def __init__(self, verbose_tool_use: bool = True) -> None:
+        """Initialize handler.
+
+        Args:
+            verbose_tool_use: Print out verbose information about tool calls.
+        """
         self.tool_count = 0
         self.previous_tool_use = None
+        self._verbose_tool_use = verbose_tool_use
 
     def __call__(self, **kwargs: Any) -> None:
         """Stream text output and tool invocations to stdout.
@@ -34,11 +39,12 @@ def __call__(self, **kwargs: Any) -> None:
             print(data, end="" if not complete else "\n")
 
         if current_tool_use and current_tool_use.get("name"):
-            tool_name = current_tool_use.get("name", "Unknown tool")
             if self.previous_tool_use != current_tool_use:
                 self.previous_tool_use = current_tool_use
                 self.tool_count += 1
-                print(f"\nTool #{self.tool_count}: {tool_name}")
+                if self._verbose_tool_use:
+                    tool_name = current_tool_use.get("name", "Unknown tool")
+                    print(f"\nTool #{self.tool_count}: {tool_name}")
 
         if complete and data:
             print("\n")

tests/strands/handlers/test_callback_handler.py

@@ -202,3 +202,25 @@ def test_composite_handler_forwards_to_all_handlers():
     # Verify each handler was called with the same arguments
     for handler in mock_handlers:
         handler.assert_called_once_with(**kwargs)
+
+
+def test_verbose_tool_use_default():
+    """Test that _verbose_tool_use defaults to True."""
+    handler = PrintingCallbackHandler()
+    assert handler._verbose_tool_use is True
+
+
+def test_verbose_tool_use_disabled(mock_print):
+    """Test that tool use output is suppressed when verbose_tool_use=False but counting still works."""
+    handler = PrintingCallbackHandler(verbose_tool_use=False)
+    assert handler._verbose_tool_use is False
+
+    current_tool_use = {"name": "test_tool", "input": {"param": "value"}}
+    handler(current_tool_use=current_tool_use)
+
+    # Should not print tool information when verbose_tool_use is False
+    mock_print.assert_not_called()
+
+    # Should still update tool count and previous_tool_use
+    assert handler.tool_count == 1
+    assert handler.previous_tool_use == current_tool_use