security(tool_loader): prevent tool name and sys modules collisions i…

src/strands/tools/loader.py

@@ -17,6 +17,8 @@
 
 logger = logging.getLogger(__name__)
 
+_TOOL_MODULE_PREFIX = "_strands_tool_"
+
 
 def load_tool_from_string(tool_string: str) -> List[AgentTool]:
     """Load tools follows strands supported input string formats.
@@ -65,7 +67,7 @@ def load_tools_from_file_path(tool_path: str) -> List[AgentTool]:
 
     module = importlib.util.module_from_spec(spec)
     # Load, or re-load, the module
-    sys.modules[module_name] = module
+    sys.modules[f"{_TOOL_MODULE_PREFIX}{module_name}"] = module
     # Execute the module to run any top level code
     spec.loader.exec_module(module)
 
@@ -200,7 +202,7 @@ def load_python_tools(tool_path: str, tool_name: str) -> List[AgentTool]:
                 raise ImportError(f"No loader available for {tool_name}")
 
             module = importlib.util.module_from_spec(spec)
-            sys.modules[tool_name] = module
+            sys.modules[f"{_TOOL_MODULE_PREFIX}{tool_name}"] = module
             spec.loader.exec_module(module)
 
             # Collect function-based tools decorated with @tool

tests/strands/tools/test_loader.py

@@ -1,12 +1,13 @@
 import os
 import re
+import sys
 import tempfile
 import textwrap
 
 import pytest
 
 from strands.tools.decorator import DecoratedFunctionTool
-from strands.tools.loader import ToolLoader, load_tools_from_file_path
+from strands.tools.loader import _TOOL_MODULE_PREFIX, ToolLoader, load_tools_from_file_path
 from strands.tools.tools import PythonAgentTool
 
 
@@ -317,3 +318,29 @@ def test_load_tools_from_file_path_module_spec_missing():
     with tempfile.NamedTemporaryFile() as f:
         with pytest.raises(ImportError, match=f"Could not create spec for {os.path.basename(f.name)}"):
             load_tools_from_file_path(f.name)
+
+
+def test_tool_module_prefix_prevents_collision():
+    """Test that tool modules are loaded with prefix to prevent sys.modules collisions."""
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".py", delete=False) as f:
+        f.write(
+            textwrap.dedent("""
+            import strands
+
+            @strands.tools.tool
+            def test_tool():
+                return "test"
+        """)
+        )
+        f.flush()
+
+        # Load the tool
+        tools = load_tools_from_file_path(f.name)
+
+        # Check that module is in sys.modules with prefix
+        module_name = os.path.basename(f.name).split(".")[0]
+        prefixed_name = f"{_TOOL_MODULE_PREFIX}{module_name}"
+
+        assert prefixed_name in sys.modules
+        assert len(tools) == 1
+        assert tools[0].tool_name == "test_tool"