diff --git a/docs/design/699-hmm-mcp-demo-users/README.md b/docs/design/699-hmm-mcp-demo-users/README.md
index ea4b393..ad582dd 100644
--- a/docs/design/699-hmm-mcp-demo-users/README.md
+++ b/docs/design/699-hmm-mcp-demo-users/README.md
@@ -24,6 +24,8 @@ vpd_token_presets.json (사용자 ID·역할·팀·테스트 문맥·mcp_token_e
 - 선택한 사용자는 자연어의 ‘나’, ‘내’, ‘우리 팀’을 해석하는 데모 문맥이다. 현재 HMM MCP의 gateway
   token은 공용이므로 이 선택 자체가 DB 행 수준 권한을 강제한다고 표시하지 않는다.
 - HMM MCP 허용 도구는 `resolve_hr_term`, `search_hr_data`, `search_hr_policy` 세 개다.
+- 호출 인자는 `tools/list`의 schema를 기준으로 생성한다. 기본 도구에도 레거시 `prompt`/`limit`를
+  강제하지 않으며 `search_hr_data`·`search_hr_policy`는 `query`, `resolve_hr_term`은 `term`을 전달한다.
 
 ## 런타임 구성
 
diff --git a/poc4_active_source_20260714/src/mcp_tool_router.py b/poc4_active_source_20260714/src/mcp_tool_router.py
index 3e09962..3dfae60 100644
--- a/poc4_active_source_20260714/src/mcp_tool_router.py
+++ b/poc4_active_source_20260714/src/mcp_tool_router.py
@@ -154,26 +154,32 @@ def build_mcp_tool_arguments(
     if not isinstance(properties, Mapping):
         properties = {}
 
-    if tool.name == preferred_tool:
-        return {"prompt": question, "limit": limit}
-    if "prompt" in properties:
-        args: dict[str, Any] = {"prompt": question}
-        if "limit" in properties:
-            args["limit"] = limit
-        elif "max_rows" in properties:
-            args["max_rows"] = limit
-        return args
-    if "question" in properties:
-        args = {"question": question}
-        if "max_rows" in properties:
-            args["max_rows"] = limit
-        elif "limit" in properties:
-            args["limit"] = limit
-        return args
-    if "query" in properties:
-        args = {"query": question}
+    # A server's default/preferred tool still has to obey its discovered schema.
+    # HMM tools use `query` and `term`; forcing the legacy `prompt`/`limit` shape
+    # makes an otherwise valid tool fail argument validation.
+    del preferred_tool
+    input_name = next(
+        (name for name in ("prompt", "question", "query", "term", "text") if name in properties),
+        "",
+    )
+    if not input_name:
+        required = tool.schema.get("required")
+        if isinstance(required, list):
+            input_name = next(
+                (
+                    str(name)
+                    for name in required
+                    if isinstance(properties.get(str(name)), Mapping)
+                    and properties[str(name)].get("type") == "string"
+                ),
+                "",
+            )
+    if input_name:
+        args: dict[str, Any] = {input_name: question}
         if "max_evidence" in properties:
             args["max_evidence"] = min(limit, 10)
+        elif "max_rows" in properties:
+            args["max_rows"] = limit
         elif "limit" in properties:
             args["limit"] = limit
         return args
diff --git a/poc4_active_source_20260714/tests/test_scenarios.py b/poc4_active_source_20260714/tests/test_scenarios.py
index c2f0f87..5ca60be 100644
--- a/poc4_active_source_20260714/tests/test_scenarios.py
+++ b/poc4_active_source_20260714/tests/test_scenarios.py
@@ -8,6 +8,7 @@ from unittest.mock import patch
 
 from src.poc4.scenarios import ScenarioConfigError, load_demo_scenarios
 from src.agent_console.profile import load_app_profile
+from src.mcp_tool_router import McpTool, build_mcp_tool_arguments
 
 
 class DemoScenarioConfigTest(unittest.TestCase):
@@ -74,6 +75,42 @@ class DemoScenarioConfigTest(unittest.TestCase):
             with self.assertRaises(ScenarioConfigError):
                 load_demo_scenarios(path)
 
+    def test_default_mcp_tool_arguments_follow_discovered_query_schema(self) -> None:
+        tool = McpTool(
+            name="search_hr_data",
+            description="",
+            schema={
+                "type": "object",
+                "properties": {"query": {"type": "string"}},
+                "required": ["query"],
+            },
+            read_only=True,
+        )
+
+        arguments = build_mcp_tool_arguments(
+            tool, "직원 E1005의 휴가 신청 내역", 50, preferred_tool="search_hr_data"
+        )
+
+        self.assertEqual(arguments, {"query": "직원 E1005의 휴가 신청 내역"})
+
+    def test_term_tool_arguments_follow_discovered_term_schema(self) -> None:
+        tool = McpTool(
+            name="resolve_hr_term",
+            description="",
+            schema={
+                "type": "object",
+                "properties": {"term": {"type": "string"}},
+                "required": ["term"],
+            },
+            read_only=True,
+        )
+
+        arguments = build_mcp_tool_arguments(
+            tool, "반차", 50, preferred_tool="search_hr_data"
+        )
+
+        self.assertEqual(arguments, {"term": "반차"})
+
 
 if __name__ == "__main__":
     unittest.main()