diff --git a/app/service/agent/bootstrap.py b/app/service/agent/bootstrap.py
index b0898f0..a25d1f3 100644
--- a/app/service/agent/bootstrap.py
+++ b/app/service/agent/bootstrap.py
@@ -18,10 +18,12 @@ from app.service.agent.governance import PlatformGovernance
 from app.service.agent.implementations.customer_service import CustomerServiceAgent
 from app.service.agent.implementations.fund_query_demo import FundQueryDemoAgent
 from app.service.agent.implementations.platform_probe import (
+    PROBE_ALT_TOOL,
     PROBE_PERMISSION,
     PROBE_TOOL,
     PlatformProbeAgent,
     ProbeEchoArgs,
+    probe_alt_tool,
     probe_echo_tool,
 )
 from app.service.agent.implementations.risk_agent import RiskAgent
@@ -187,6 +189,14 @@ def get_agent_factory() -> AgentFactory:
         required_permission=PROBE_PERMISSION,
         allowed_roles=("admin",),
     ))
+    # 第二个探针工具：让"有白名单但不含该工具"的分支可被构造（见 platform_probe 的说明）
+    registry.register(ToolDefinition(
+        name=PROBE_ALT_TOOL,
+        input_model=ProbeEchoArgs,
+        handler=cast(Any, probe_alt_tool),
+        required_permission=PROBE_PERMISSION,
+        allowed_roles=("admin",),
+    ))
     registry.register(ToolDefinition(
         name="check_suitability",
         input_model=SuitabilityToolInput,
diff --git a/app/service/agent/implementations/platform_probe.py b/app/service/agent/implementations/platform_probe.py
index 5dc2b33..69a4ea5 100644
--- a/app/service/agent/implementations/platform_probe.py
+++ b/app/service/agent/implementations/platform_probe.py
@@ -26,6 +26,11 @@ from app.service.agent.base import BaseAgent
 AGENT_TYPE = "platform_probe"
 INTENT_PROBE = "probe"
 PROBE_TOOL = "probe_echo"
+# 第二个探针工具。**存在的唯一理由**：让"工具不在白名单"这一分支可被触发。
+# `governance.resolve` 取的是「发布白名单 ∩ 代码声明的 allowed_tools」，配置**只能缩小
+# 不能放大**；所以 Agent 只有一个工具时，白名单要么为空、要么正好包含它，
+# 永远构造不出"有白名单、但不含被调用的那个工具"的场景——这是我做端到端验证时撞到的。
+PROBE_ALT_TOOL = "probe_alt"
 PROBE_PERMISSION = "probe:read"
 
 
@@ -43,6 +48,11 @@ async def probe_echo_tool(arguments: BaseModel, context: RequestContext) -> dict
     return {"echo": note, "trace_id": context.trace_id}
 
 
+async def probe_alt_tool(arguments: BaseModel, context: RequestContext) -> dict[str, Any]:
+    """备用探针工具：只为让"工具不在白名单"的分支可被构造，与 probe_echo 同样只读。"""
+    return {"alt": True, "trace_id": context.trace_id}
+
+
 class PlatformProbeAgent(BaseAgent):
     """基座探针：只用于验证工具链路的拒绝行为，不承载任何业务。"""
 
@@ -51,7 +61,7 @@ class PlatformProbeAgent(BaseAgent):
         version="1.0.0",
         allowed_roles=("admin",),
         allowed_portals=("api",),
-        allowed_tools=(PROBE_TOOL,),
+        allowed_tools=(PROBE_TOOL, PROBE_ALT_TOOL),
         supported_intents=(INTENT_PROBE,),
     )