fix(workflow): exclude workflow tool from task agent inheritance to prevent recursion

src/strands_tools/workflow.py

@@ -328,15 +328,23 @@ def _create_task_agent(self, task: Dict) -> Agent:
             filtered_tools = []
             if task_tools and self.parent_agent and hasattr(self.parent_agent, "tool_registry"):
                 # Filter parent agent tools to only include specified tool names
+                # ALWAYS exclude 'workflow' tool to prevent recursion
                 available_tools = self.parent_agent.tool_registry.registry
                 for tool_name in task_tools:
+                    if tool_name == "workflow":
+                        logger.warning("Excluding 'workflow' tool from task agent to prevent recursion")
+                        continue
                     if tool_name in available_tools:
                         filtered_tools.append(available_tools[tool_name])
                     else:
                         logger.warning(f"Tool '{tool_name}' not found in parent agent's tool registry")
             elif self.parent_agent and hasattr(self.parent_agent, "tool_registry"):
-                # Inherit all tools from parent if none specified
-                filtered_tools = list(self.parent_agent.tool_registry.registry.values())
+                # Inherit all tools from parent EXCEPT the workflow tool to prevent recursion
+                for tool_name, tool_obj in self.parent_agent.tool_registry.registry.items():
+                    if tool_name == "workflow":
+                        logger.debug("Automatically excluding 'workflow' tool from task agent to prevent recursion")
+                        continue
+                    filtered_tools.append(tool_obj)
 
             # Configure model
             selected_model = None

tests/test_workflow.py

@@ -572,6 +572,100 @@ def test_get_ready_tasks_with_completed_dependencies(self, mock_parent_agent):
         assert len(ready_tasks) == 1
         assert ready_tasks[0]["task_id"] == "task2"
 
+    def test_create_task_agent_excludes_workflow_tool_explicit(self, mock_parent_agent):
+        """Test that explicitly requesting 'workflow' tool in task tools list is excluded to prevent recursion."""
+        mock_parent_agent.tool_registry.registry["workflow"] = MagicMock()
+
+        with patch("strands_tools.workflow.Agent") as mock_agent_class:
+            mock_agent_class.return_value = MagicMock()
+
+            manager = workflow_module.WorkflowManager(mock_parent_agent)
+            manager.parent_agent = mock_parent_agent
+
+            task = {
+                "task_id": "test_task",
+                "description": "Test task",
+                "tools": ["calculator", "workflow"],
+            }
+
+            manager._create_task_agent(task)
+
+            call_kwargs = mock_agent_class.call_args.kwargs
+            # Should have only 1 tool (calculator), workflow excluded
+            assert len(call_kwargs["tools"]) == 1
+            assert call_kwargs["tools"][0] == mock_parent_agent.tool_registry.registry["calculator"]
+
+    def test_create_task_agent_excludes_workflow_tool_inherit_all(self, mock_parent_agent):
+        """Test that workflow tool is automatically excluded when inheriting all tools from parent."""
+        mock_parent_agent.tool_registry.registry["workflow"] = MagicMock()
+
+        with patch("strands_tools.workflow.Agent") as mock_agent_class:
+            mock_agent_class.return_value = MagicMock()
+
+            manager = workflow_module.WorkflowManager(mock_parent_agent)
+            manager.parent_agent = mock_parent_agent
+
+            # No tools specified - should inherit all except workflow
+            task = {
+                "task_id": "test_task",
+                "description": "Test task",
+            }
+
+            manager._create_task_agent(task)
+
+            call_kwargs = mock_agent_class.call_args.kwargs
+            tool_count = len(call_kwargs["tools"])
+            # Parent has 8 original tools + workflow = 9 total, workflow excluded = 8
+            assert tool_count == 8
+            # Verify workflow tool is not in the list
+            workflow_tool = mock_parent_agent.tool_registry.registry["workflow"]
+            assert workflow_tool not in call_kwargs["tools"]
+
+    def test_create_task_agent_only_workflow_tool_requested(self, mock_parent_agent):
+        """Test that requesting only 'workflow' tool results in empty tools list."""
+        mock_parent_agent.tool_registry.registry["workflow"] = MagicMock()
+
+        with patch("strands_tools.workflow.Agent") as mock_agent_class:
+            mock_agent_class.return_value = MagicMock()
+
+            manager = workflow_module.WorkflowManager(mock_parent_agent)
+            manager.parent_agent = mock_parent_agent
+
+            task = {
+                "task_id": "test_task",
+                "description": "Test task",
+                "tools": ["workflow"],
+            }
+
+            manager._create_task_agent(task)
+
+            call_kwargs = mock_agent_class.call_args.kwargs
+            # Should have 0 tools since only workflow was requested and it's excluded
+            assert len(call_kwargs["tools"]) == 0
+
+    def test_create_task_agent_without_workflow_in_registry(self, mock_parent_agent):
+        """Test that task agent creation works normally when workflow is not in parent registry."""
+        # mock_parent_agent does not have 'workflow' in registry by default
+        assert "workflow" not in mock_parent_agent.tool_registry.registry
+
+        with patch("strands_tools.workflow.Agent") as mock_agent_class:
+            mock_agent_class.return_value = MagicMock()
+
+            manager = workflow_module.WorkflowManager(mock_parent_agent)
+            manager.parent_agent = mock_parent_agent
+
+            # No tools specified - inherits all from parent
+            task = {
+                "task_id": "test_task",
+                "description": "Test task",
+            }
+
+            manager._create_task_agent(task)
+
+            call_kwargs = mock_agent_class.call_args.kwargs
+            # Should have all 8 original tools
+            assert len(call_kwargs["tools"]) == 8
+
 
 class TestWorkflowEdgeCases:
     """Test edge cases and error conditions."""