diff --git a/studio/frontend/src/components/assistant-ui/thread.tsx b/studio/frontend/src/components/assistant-ui/thread.tsx
index d3cbb2d0a8..d4f0a0b66d 100644
--- a/studio/frontend/src/components/assistant-ui/thread.tsx
+++ b/studio/frontend/src/components/assistant-ui/thread.tsx
@@ -1149,7 +1149,10 @@ const RagToggle: FC = () => {
   const setRagToolEnabled = useChatRuntimeStore((s) => s.setRagToolEnabled);
   const ragSource = useChatRuntimeStore((s) => s.ragSource);
   const setRagSource = useChatRuntimeStore((s) => s.setRagSource);
-  const disabled = !modelLoaded;
+  const supportsTools = useChatRuntimeStore((s) => s.supportsTools);
+  // RAG runs through the local search_knowledge_base tool, so it needs
+  // tool-calling support (mirrors shared-composer's ragDisabled).
+  const disabled = !modelLoaded || !supportsTools;
   return (
     <button
       type="button"
@@ -1165,9 +1168,11 @@ const RagToggle: FC = () => {
       data-active={ragToolEnabled && !disabled ? "true" : "false"}
       aria-label={ragToolEnabled ? "Disable RAG" : "Enable RAG"}
       title={
-        ragToolEnabled
-          ? "RAG on — the model can search your attached documents"
-          : "Enable RAG — let the model search your documents"
+        disabled
+          ? "RAG needs a model that supports tool calling"
+          : ragToolEnabled
+            ? "RAG on — the model can search your attached documents"
+            : "Enable RAG — let the model search your documents"
       }
     >
       <BookOpenIcon className="size-3.5" />
diff --git a/studio/frontend/src/features/chat/shared-composer.tsx b/studio/frontend/src/features/chat/shared-composer.tsx
index abd06624c8..f516f44812 100644
--- a/studio/frontend/src/features/chat/shared-composer.tsx
+++ b/studio/frontend/src/features/chat/shared-composer.tsx
@@ -518,6 +518,11 @@ export function SharedComposer({
   // Images pill is only ever lit on OpenAI cloud's Responses-API models
   // and Gemini Nano Banana family. No local tool runtime fallback.
   const showImagePill = supportsBuiltinImageGeneration;
+  // RAG retrieval runs entirely through the local search_knowledge_base
+  // tool, so it needs the tool-calling loop. No external-builtin RAG
+  // equivalent — gate purely on supportsTools (mirrors web/code when not
+  // backed by a provider builtin).
+  const ragDisabled = !modelLoaded || !supportsTools;
   // Fetch pill: Anthropic-only (web_fetch_20250910 / web_fetch_20260209).
   const webFetchDisabled = !modelLoaded || !supportsBuiltinWebFetch;
   const showWebFetchPill = supportsBuiltinWebFetch;
@@ -1405,7 +1410,7 @@ export function SharedComposer({
           {/* Master RAG toggle; sidebar Retrieval section configures the rest. */}
           <button
             type="button"
-            disabled={!modelLoaded}
+            disabled={ragDisabled}
             onClick={() => {
               const next = !ragToolEnabled;
               setRagToolEnabled(next);
@@ -1414,12 +1419,14 @@ export function SharedComposer({
               }
             }}
             className="composer-pill-btn"
-            data-active={ragToolEnabled && modelLoaded ? "true" : "false"}
+            data-active={ragToolEnabled && !ragDisabled ? "true" : "false"}
             aria-label={ragToolEnabled ? "Disable RAG" : "Enable RAG"}
             title={
-              ragToolEnabled
-                ? "RAG on — the model can search your attached documents"
-                : "Enable RAG — let the model search your documents"
+              ragDisabled
+                ? "RAG needs a model that supports tool calling"
+                : ragToolEnabled
+                  ? "RAG on — the model can search your attached documents"
+                  : "Enable RAG — let the model search your documents"
             }
           >
             <BookOpenIcon className="size-3.5" />