优化查询代码，优化工具代码

backend/app/tools/web_search.py

@@ -0,0 +1,18 @@
+"""
+联网搜索工具
+"""
+
+from langchain_core.tools import tool
+from backend.app.logger import info
+
+
+@tool
+def web_search(query: str) -> str:
+    """联网搜索获取最新信息"""
+    info(f"[Tool] web_search: {query[:30]}...")
+    try:
+        from backend.app.core.web_search import web_search as search_fn
+        return search_fn(query, max_results=5)
+    except Exception as e:
+        info(f"[Tool] web_search 失败: {e}")
+        return f"联网搜索失败: {str(e)}"