diff --git a/vibn-frontend/lib/ai/vibn-tools.ts b/vibn-frontend/lib/ai/vibn-tools.ts
index e90f061..e7cad6e 100644
--- a/vibn-frontend/lib/ai/vibn-tools.ts
+++ b/vibn-frontend/lib/ai/vibn-tools.ts
@@ -1397,7 +1397,8 @@ After this returns, ALWAYS call apps_deploy { uuid } to regenerate the live Trae
     name: "dev_server_start",
     description:
       "Launch a long-running process inside the dev container (e.g. `npm run dev`, `python -m http.server`). " +
-      "Returns a preview URL the user can open in a browser. The process keeps running across shell.exec calls. " +
+      "Returns a preview URL the user can open in a browser. On failure (ok=false), the tool automatically returns the latest 50 lines of server logs in the 'logs' field - read this field immediately to locate compilation or type errors. " +
+      "The process keeps running across shell.exec calls. " +
       "IMPORTANT: bind your server to 0.0.0.0 — we set HOST=0.0.0.0 + PORT=<port> automatically, but verify the framework respects them.",
     parameters: {
       type: "OBJECT",