diff --git a/client/src/hooks/Input/mentions.spec.ts b/client/src/hooks/Input/mentions.spec.ts
new file mode 100644
index 0000000000..4eefed12c5
--- /dev/null
+++ b/client/src/hooks/Input/mentions.spec.ts
@@ -0,0 +1,50 @@
+import { EModelEndpoint } from 'librechat-data-provider';
+import { filterMentionEndpoints } from './mentions';
+
+describe('filterMentionEndpoints', () => {
+  const endpoints = [EModelEndpoint.anthropic, EModelEndpoint.bedrock, EModelEndpoint.agents];
+
+  it('limits mention endpoints to model spec addedEndpoints', () => {
+    const result = filterMentionEndpoints({
+      endpoints,
+      includedEndpoints: new Set([EModelEndpoint.agents]),
+      includeAssistants: true,
+      hasAgentAccess: true,
+    });
+
+    expect(result).toEqual([EModelEndpoint.agents]);
+  });
+
+  it('keeps provider endpoints when no model spec allow-list is configured', () => {
+    const result = filterMentionEndpoints({
+      endpoints,
+      includedEndpoints: new Set(),
+      includeAssistants: true,
+      hasAgentAccess: true,
+    });
+
+    expect(result).toEqual(endpoints);
+  });
+
+  it('excludes agents when the user lacks agent access', () => {
+    const result = filterMentionEndpoints({
+      endpoints,
+      includedEndpoints: new Set([EModelEndpoint.agents]),
+      includeAssistants: true,
+      hasAgentAccess: false,
+    });
+
+    expect(result).toEqual([]);
+  });
+
+  it('excludes assistants when they are not included for the mention menu', () => {
+    const result = filterMentionEndpoints({
+      endpoints: [EModelEndpoint.assistants, EModelEndpoint.azureAssistants, EModelEndpoint.openAI],
+      includedEndpoints: new Set(),
+      includeAssistants: false,
+      hasAgentAccess: true,
+    });
+
+    expect(result).toEqual([EModelEndpoint.openAI]);
+  });
+});
diff --git a/client/src/hooks/Input/mentions.ts b/client/src/hooks/Input/mentions.ts
new file mode 100644
index 0000000000..7190b9ae35
--- /dev/null
+++ b/client/src/hooks/Input/mentions.ts
@@ -0,0 +1,31 @@
+import { EModelEndpoint, isAgentsEndpoint, isAssistantsEndpoint } from 'librechat-data-provider';
+
+export function filterMentionEndpoints({
+  endpoints,
+  includedEndpoints,
+  includeAssistants,
+  hasAgentAccess,
+}: {
+  endpoints: Array<EModelEndpoint | string>;
+  includedEndpoints: Set<string>;
+  includeAssistants: boolean;
+  hasAgentAccess: boolean;
+}) {
+  const hasEndpointAllowList = includedEndpoints.size > 0;
+
+  return endpoints.filter((endpoint) => {
+    if (!includeAssistants && isAssistantsEndpoint(endpoint)) {
+      return false;
+    }
+
+    if (isAgentsEndpoint(endpoint) && !hasAgentAccess) {
+      return false;
+    }
+
+    if (hasEndpointAllowList && !includedEndpoints.has(endpoint)) {
+      return false;
+    }
+
+    return true;
+  });
+}
diff --git a/client/src/hooks/Input/useMentions.ts b/client/src/hooks/Input/useMentions.ts
index 0c16bcc1ce..420f823e23 100644
--- a/client/src/hooks/Input/useMentions.ts
+++ b/client/src/hooks/Input/useMentions.ts
@@ -23,6 +23,7 @@ import { useAgentsMapContext } from '~/Providers/AgentsMapContext';
 import { mapEndpoints, getPresetTitle } from '~/utils';
 import { EndpointIcon } from '~/components/Endpoints';
 import useHasAccess from '~/hooks/Roles/useHasAccess';
+import { filterMentionEndpoints } from './mentions';
 
 const defaultInterface = getConfigDefaults().interface;
 
@@ -82,7 +83,25 @@ export default function useMentions({
     () => startupConfig?.interface ?? defaultInterface,
     [startupConfig?.interface],
   );
-  const agentQueryEnabled = hasAgentAccess && interfaceConfig.modelSelect === true;
+  const includedEndpoints = useMemo(
+    () => new Set(startupConfig?.modelSpecs?.addedEndpoints ?? []),
+    [startupConfig?.modelSpecs?.addedEndpoints],
+  );
+  const validEndpoints = useMemo(
+    () =>
+      filterMentionEndpoints({
+        endpoints,
+        includedEndpoints,
+        includeAssistants,
+        hasAgentAccess,
+      }),
+    [endpoints, includedEndpoints, includeAssistants, hasAgentAccess],
+  );
+  const validEndpointSet = useMemo(() => new Set(validEndpoints), [validEndpoints]);
+  const agentQueryEnabled =
+    hasAgentAccess &&
+    interfaceConfig.modelSelect === true &&
+    (includedEndpoints.size === 0 || includedEndpoints.has(EModelEndpoint.agents));
   const { data: agentsList = null, isLoading: isLoadingAgents } = useListAgentsQuery(
     { requiredPermission: PermissionBits.VIEW },
     {
@@ -152,11 +171,6 @@ export default function useMentions({
   }, [startupConfig, agentsMap]);
 
   const options: MentionOption[] = useMemo(() => {
-    let validEndpoints = endpoints;
-    if (!includeAssistants) {
-      validEndpoints = endpoints.filter((endpoint) => !isAssistantsEndpoint(endpoint));
-    }
-
     const modelOptions = validEndpoints.flatMap((endpoint) => {
       if (isAssistantsEndpoint(endpoint) || isAgentsEndpoint(endpoint)) {
         return [];
@@ -207,14 +221,18 @@ export default function useMentions({
           size: 20,
         }),
       })),
-      ...(interfaceConfig.modelSelect === true ? (agentsList ?? []) : []),
+      ...(interfaceConfig.modelSelect === true && validEndpointSet.has(EModelEndpoint.agents)
+        ? (agentsList ?? [])
+        : []),
       ...(endpointsConfig?.[EModelEndpoint.assistants] &&
       includeAssistants &&
+      validEndpointSet.has(EModelEndpoint.assistants) &&
       interfaceConfig.modelSelect === true
         ? assistantListMap[EModelEndpoint.assistants] || []
         : []),
       ...(endpointsConfig?.[EModelEndpoint.azureAssistants] &&
       includeAssistants &&
+      validEndpointSet.has(EModelEndpoint.azureAssistants) &&
       interfaceConfig.modelSelect === true
         ? assistantListMap[EModelEndpoint.azureAssistants] || []
         : []),
@@ -241,11 +259,12 @@ export default function useMentions({
     return mentions;
   }, [
     presets,
-    endpoints,
     modelSpecs,
     agentsList,
     assistantMap,
     modelsConfig,
+    validEndpoints,
+    validEndpointSet,
     endpointsConfig,
     assistantListMap,
     includeAssistants,