Refactor

open-sse/utils/claudeCloaking.js

@@ -40,8 +40,11 @@ export function cloakClaudeTools(body) {
   const clientToolNames = new Set();
   const clientDeclarations = [];
 
-  // All client tools get renamed with suffix
+  // All client tools get renamed with suffix.
+  // Built-in server tools (web_search_20250305, etc.) carry a `type` and require
+  // an exact reserved `name` — never suffix those or Claude rejects the request.
   for (const tool of tools) {
+    if (tool.type) { clientDeclarations.push(tool); continue; }
     const suffixed = suffix(tool.name);
     toolNameMap.set(suffixed, tool.name);
     clientToolNames.add(tool.name);