Add usage limit feature to BaseTool class

- Add max_usage_count and current_usage_count attributes to BaseTool
- Implement usage limit checking in ToolUsage._use method
- Add comprehensive tests for usage limit functionality
- Maintain backward compatibility with None default for unlimited usage

Co-Authored-By: Joe Moura <joao@crewai.com>

tests/tools/test_tool_usage_limit.py

@@ -0,0 +1,68 @@
+import pytest
+from unittest.mock import MagicMock, patch
+
+from crewai.tools import BaseTool, tool
+
+
+def test_tool_usage_limit():
+    """Test that tools respect usage limits."""
+    class LimitedTool(BaseTool):
+        name: str = "Limited Tool"
+        description: str = "A tool with usage limits for testing"
+        max_usage_count: int = 2
+
+        def _run(self, input_text: str) -> str:
+            return f"Processed {input_text}"
+
+    tool = LimitedTool()
+    
+    result1 = tool.run(input_text="test1")
+    assert result1 == "Processed test1"
+    assert tool.current_usage_count == 1
+    
+    result2 = tool.run(input_text="test2")
+    assert result2 == "Processed test2"
+    assert tool.current_usage_count == 2
+
+
+def test_unlimited_tool_usage():
+    """Test that tools without usage limits work normally."""
+    class UnlimitedTool(BaseTool):
+        name: str = "Unlimited Tool"
+        description: str = "A tool without usage limits"
+
+        def _run(self, input_text: str) -> str:
+            return f"Processed {input_text}"
+
+    tool = UnlimitedTool()
+    
+    for i in range(5):
+        result = tool.run(input_text=f"test{i}")
+        assert result == f"Processed test{i}"
+        assert tool.current_usage_count == i + 1
+
+
+def test_tool_decorator_with_usage_limit():
+    """Test usage limit with @tool decorator."""
+    @tool("Test Tool", max_usage_count=3)
+    def test_tool(input_text: str) -> str:
+        """A test tool."""
+        return f"Result: {input_text}"
+    
+    assert test_tool.max_usage_count == 3
+    assert test_tool.current_usage_count == 0
+
+    result = test_tool.run(input_text="test")
+    assert result == "Result: test"
+    assert test_tool.current_usage_count == 1
+
+
+def test_default_unlimited_usage():
+    """Test that tools have unlimited usage by default."""
+    @tool("Default Tool")
+    def default_tool(input_text: str) -> str:
+        """A default tool."""
+        return f"Result: {input_text}"
+    
+    assert default_tool.max_usage_count is None
+    assert default_tool.current_usage_count == 0