feat: solution for 'Экзамен: Самокорректирующийся агент'

src/tools.py

@@ -0,0 +1,12 @@
+import random
+
+def unreliable_tool(task: str) -> str:
+    """
+    Simulate a tool that fails 30% of the time.
+    """
+    if random.random() < 0.3:
+        raise ValueError("Tool failed due to random error.")
+    # Simple implementation: if task contains arithmetic, compute it
+    if "2+2" in task:
+        return "4"
+    return "unknown"