diff --git a/app/agent/tools/impl/api.py b/app/agent/tools/impl/api.py
index c5e39f740..c24e6776f 100644
--- a/app/agent/tools/impl/api.py
+++ b/app/agent/tools/impl/api.py
@@ -83,11 +83,15 @@ class MoviePilotApiTool(MoviePilotTool):
     ]
     description: str = (
         "Call allowlisted MoviePilot business APIs, including versioned automatic media classification. "
-        "Use the domain Skill to select operation_id, "
+        "Read the matching domain Skill before the first call, then select operation_id, "
         "parameters, and failure handling. For collection counts, use the smallest documented "
         "page and read collection.total_count instead of querying the database after item "
         "truncation. External MCP tools/list exposes one complete oneOf branch per operation. "
-        "Arbitrary URLs, commands, and authentication endpoints are forbidden."
+        "Common contracts: subscription.find uses path_params.media_id and query.media_source; "
+        "subscription.list accepts only query.page and query.count; site.list accepts only "
+        "query.page, query.count, query.name, and query.status; download.add puts torrent_in "
+        "with title/enclosure beside media_source/media_id in body. Arbitrary URLs, commands, "
+        "and authentication endpoints are forbidden."
     )
     require_admin: bool = False
     args_schema: Type[BaseModel] = MoviePilotApiInput
diff --git a/tests/test_agent_api_gateway.py b/tests/test_agent_api_gateway.py
index 588ad819a..c1c5df4ee 100644
--- a/tests/test_agent_api_gateway.py
+++ b/tests/test_agent_api_gateway.py
@@ -148,6 +148,16 @@ def test_api_tool_message_displays_secret_safe_major_parameters() -> None:
     assert "sk-secret-value" not in secret_message
 
 
+def test_api_tool_description_keeps_split_skill_contracts_visible_at_call_time() -> None:
+    """即使模型尚未读取 Skill，网关描述也要提示最容易误用的字段位置。"""
+    description = MoviePilotApiTool(session_id="session", user_id="api_user").description
+
+    assert "subscription.find uses path_params.media_id" in description
+    assert "subscription.list accepts only query.page and query.count" in description
+    assert "site.list accepts only query.page, query.count, query.name, and query.status" in description
+    assert "download.add puts torrent_in" in description
+
+
 def test_music_operations_expose_bidirectional_artist_album_navigation() -> None:
     """音乐 Skill 必须完整暴露作品到作者、作者到作品及关联浏览合同。"""
     schema = MoviePilotApiTool(session_id="session", user_id="api_user").get_mcp_input_schema()