diff --git a/artifacts/toolrate/src/pages/tool-detail.tsx b/artifacts/toolrate/src/pages/tool-detail.tsx
index b5ab11d..925f604 100644
--- a/artifacts/toolrate/src/pages/tool-detail.tsx
+++ b/artifacts/toolrate/src/pages/tool-detail.tsx
@@ -92,8 +92,7 @@ export default function ToolDetail() {
   useEffect(() => {
     if (!id) return;
     setSimilarLoading(true);
-    customFetch(`/api/tools/${id}/similar`)
-      .then((r) => r.json())
+    customFetch<any>(`/api/tools/${id}/similar`)
       .then((data) => setSimilarData(data))
       .catch(() => {})
       .finally(() => setSimilarLoading(false));
@@ -102,30 +101,26 @@ export default function ToolDetail() {
   async function handleCreateRelation() {
     if (!linkToolId) return;
     try {
-      const res = await customFetch(`/api/tools/${id}/relations`, {
+      await customFetch(`/api/tools/${id}/relations`, {
         method: "POST",
         body: JSON.stringify({ relatedToolId: Number(linkToolId), relationType: linkType, notes: linkNotes || undefined }),
       });
-      if (!res.ok) { const e = await res.json(); throw new Error(e.error); }
       toast({ title: "Relation created" });
       setLinkDialogOpen(false);
       setLinkToolId("");
       setLinkNotes("");
       setLinkType("similar");
-      const r = await customFetch(`/api/tools/${id}/similar`).then((r2) => r2.json());
-      setSimilarData(r);
+      setSimilarData(await customFetch<any>(`/api/tools/${id}/similar`));
     } catch (err: any) {
-      toast({ title: "Failed to create relation", description: err.message, variant: "destructive" });
+      toast({ title: "Failed to create relation", description: err.data?.error ?? err.message, variant: "destructive" });
     }
   }
 
   async function handleDeleteRelation(relationId: number) {
     try {
-      const res = await customFetch(`/api/tools/relations/${relationId}`, { method: "DELETE" });
-      if (!res.ok) throw new Error("Failed to delete");
+      await customFetch(`/api/tools/relations/${relationId}`, { method: "DELETE" });
       toast({ title: "Relation deleted" });
-      const r = await customFetch(`/api/tools/${id}/similar`).then((r2) => r2.json());
-      setSimilarData(r);
+      setSimilarData(await customFetch<any>(`/api/tools/${id}/similar`));
     } catch {
       toast({ title: "Failed to delete relation", variant: "destructive" });
     }
@@ -151,17 +146,13 @@ export default function ToolDetail() {
     if (costAmount) body.cost = costAmount;
     if (costRenewal) body.renewalDate = costRenewal;
     try {
-      const res = await customFetch(url, {
-        method,
-        body: JSON.stringify(body),
-      });
-      if (!res.ok) { const e = await res.json(); throw new Error(e.error); }
+      await customFetch(url, { method, body: JSON.stringify(body) });
       toast({ title: editCost ? "Cost updated" : "Cost added" });
       setCostDialogOpen(false);
       resetCostForm();
       setCosts(await customFetch<any[]>(`/api/tools/${id}/costs`));
     } catch (err: any) {
-      toast({ title: "Failed to save cost", description: err.message, variant: "destructive" });
+      toast({ title: "Failed to save cost", description: err.data?.error ?? err.message, variant: "destructive" });
     }
   }
 
@@ -186,8 +177,7 @@ export default function ToolDetail() {
 
   async function handleDeleteCost(costId: number) {
     try {
-      const res = await customFetch(`/api/costs/${costId}`, { method: "DELETE" });
-      if (!res.ok) throw new Error("Failed to delete");
+      await customFetch(`/api/costs/${costId}`, { method: "DELETE" });
       toast({ title: "Cost deleted" });
       setCosts(await customFetch<any[]>(`/api/tools/${id}/costs`));
     } catch {