diff --git a/tests/alerts/test_alert_deriver_base.py b/tests/alerts/test_alert_deriver_base.py
new file mode 100644
index 0000000..f064ae7
--- /dev/null
+++ b/tests/alerts/test_alert_deriver_base.py
@@ -0,0 +1,114 @@
+"""Tests for AlertDeriver.get_threshold and get_threshold_async."""
+
+from __future__ import annotations
+
+from typing import Any
+
+import pytest
+
+from agent_debugger_sdk.core.events import TraceEvent
+from collector.alerts.base import AlertDeriver
+
+
+class _StubDeriver(AlertDeriver):
+    """Minimal concrete AlertDeriver for exercising base-class behavior."""
+
+    def derive(self, events: list[TraceEvent]) -> list[dict[str, Any]]:
+        return []
+
+
+def test_get_threshold_no_policy_getter():
+    deriver = _StubDeriver(policy_getter=None)
+
+    result = deriver.get_threshold("tool_loop", default_threshold=1.5)
+
+    assert result == 1.5
+
+
+def test_get_threshold_sync_policy_returns_threshold_value():
+    def policy_getter(alert_type: str, agent_name: str | None) -> dict:
+        return {"enabled": True, "threshold_value": 3.0}
+
+    deriver = _StubDeriver(policy_getter=policy_getter)
+
+    result = deriver.get_threshold("tool_loop", default_threshold=1.0)
+
+    assert result == 3.0
+
+
+def test_get_threshold_sync_policy_disabled_returns_default():
+    def policy_getter(alert_type: str, agent_name: str | None) -> dict:
+        return {"enabled": False, "threshold_value": 3.0}
+
+    deriver = _StubDeriver(policy_getter=policy_getter)
+
+    result = deriver.get_threshold("tool_loop", default_threshold=1.0)
+
+    assert result == 1.0
+
+
+def test_get_threshold_sync_policy_none_returns_default():
+    def policy_getter(alert_type: str, agent_name: str | None) -> None:
+        return None
+
+    deriver = _StubDeriver(policy_getter=policy_getter)
+
+    result = deriver.get_threshold("tool_loop", default_threshold=2.0)
+
+    assert result == 2.0
+
+
+def test_get_threshold_async_policy_getter_returns_default_immediately():
+    async def policy_getter(alert_type: str, agent_name: str | None) -> dict:
+        return {"enabled": True, "threshold_value": 9.0}
+
+    deriver = _StubDeriver(policy_getter=policy_getter)
+
+    result = deriver.get_threshold("tool_loop", default_threshold=1.0)
+
+    assert result == 1.0
+
+
+@pytest.mark.asyncio
+async def test_get_threshold_async_no_policy_getter():
+    deriver = _StubDeriver(policy_getter=None)
+
+    result = await deriver.get_threshold_async("tool_loop", default_threshold=1.5)
+
+    assert result == 1.5
+
+
+@pytest.mark.asyncio
+async def test_get_threshold_async_sync_policy_getter():
+    def policy_getter(alert_type: str, agent_name: str | None) -> dict:
+        return {"enabled": True, "threshold_value": 4.0}
+
+    deriver = _StubDeriver(policy_getter=policy_getter)
+
+    result = await deriver.get_threshold_async("tool_loop", default_threshold=1.0)
+
+    assert result == 4.0
+
+
+@pytest.mark.asyncio
+async def test_get_threshold_async_async_policy_getter_awaits():
+    async def policy_getter(alert_type: str, agent_name: str | None) -> dict:
+        return {"enabled": True, "threshold_value": 7.0}
+
+    deriver = _StubDeriver(policy_getter=policy_getter)
+
+    result = await deriver.get_threshold_async("tool_loop", default_threshold=1.0)
+
+    assert result == 7.0
+
+
+@pytest.mark.asyncio
+async def test_get_threshold_async_disabled_policy_returns_default():
+    async def policy_getter(alert_type: str, agent_name: str | None) -> dict:
+        return {"enabled": False, "threshold_value": 7.0}
+
+    deriver = _StubDeriver(policy_getter=policy_getter)
+
+    result = await deriver.get_threshold_async("tool_loop", default_threshold=1.0)
+
+    assert result == 1.0