diff --git a/litellm/proxy/guardrails/guardrail_hooks/agent_365/agent_365.py b/litellm/proxy/guardrails/guardrail_hooks/agent_365/agent_365.py
index 0d45b5ff238..34c4d67a829 100644
--- a/litellm/proxy/guardrails/guardrail_hooks/agent_365/agent_365.py
+++ b/litellm/proxy/guardrails/guardrail_hooks/agent_365/agent_365.py
@@ -304,11 +304,17 @@ class Agent365Guardrail(CustomGuardrail):
                 reason="the Agent 365 endpoint returned a non-object JSON body",
             )
         verdict: Final[_EvaluateResponse] = parsed_verdict
+        allowed: Final = verdict.get("allowed")
+        if not isinstance(allowed, bool):
+            return self._handle_unavailable(
+                data=data,
+                tool_name=tool_name,
+                reason="the Agent 365 endpoint returned a verdict without a boolean 'allowed' field",
+            )
         raw_defender: Final = verdict.get("defender")
         defender: Final = raw_defender if isinstance(raw_defender, dict) else _DefenderResult()
         raw_correlation_id: Final = verdict.get("correlationId")
         correlation_id: Final = raw_correlation_id if isinstance(raw_correlation_id, str) else None
-        allowed: Final = verdict.get("allowed") is True
         self._record_verdict(
             data=data,
             verdict="Allow" if allowed else "Block",
diff --git a/tests/test_litellm/proxy/guardrails/guardrail_hooks/test_agent_365.py b/tests/test_litellm/proxy/guardrails/guardrail_hooks/test_agent_365.py
index e9cdf9318a6..2f037418927 100644
--- a/tests/test_litellm/proxy/guardrails/guardrail_hooks/test_agent_365.py
+++ b/tests/test_litellm/proxy/guardrails/guardrail_hooks/test_agent_365.py
@@ -592,6 +592,37 @@ class TestMalformedResponses:
             await _run(guardrail, _mcp_data())
         assert exc_info.value.status_code == 503
 
+    @pytest.mark.asyncio
+    @pytest.mark.parametrize(
+        "verdict",
+        [{}, {"allowed": None}, {"allowed": "true"}, {"allowed": 1}, {"allowed": "false"}],
+        ids=["missing", "null", "string-true", "int-one", "string-false"],
+    )
+    async def test_evaluate_non_boolean_allowed_fail_closed(self, verdict: dict):
+        handler: Final = FakeHandler([_token_response(), _response(200, verdict)])
+        guardrail: Final = _make_guardrail(handler)
+        data: Final = _mcp_data()
+        with pytest.raises(HTTPException) as exc_info:
+            await _run(guardrail, data)
+        assert exc_info.value.status_code == 503
+        assert "boolean 'allowed'" in exc_info.value.detail["message"]
+        assert _guardrail_info(data)["guardrail_response"]["verdict"] == "Unavailable"
+
+    @pytest.mark.asyncio
+    @pytest.mark.parametrize(
+        "verdict",
+        [{}, {"allowed": None}, {"allowed": "true"}, {"allowed": 1}, {"allowed": "false"}],
+        ids=["missing", "null", "string-true", "int-one", "string-false"],
+    )
+    async def test_evaluate_non_boolean_allowed_fail_open(self, verdict: dict):
+        handler: Final = FakeHandler([_token_response(), _response(200, verdict)])
+        guardrail: Final = _make_guardrail(handler, unreachable_fallback="fail_open")
+        data: Final = _mcp_data()
+        result: Final = await _run(guardrail, data)
+        assert result is data
+        assert _guardrail_info(data)["guardrail_response"]["verdict"] == "Unscanned"
+        assert _guardrail_info(data)["guardrail_status"] == "guardrail_failed_to_respond"
+
     @pytest.mark.asyncio
     async def test_bad_expires_in_still_allows(self):
         handler: Final = FakeHandler(