diff --git a/api/server/controllers/mcpApps.js b/api/server/controllers/mcpApps.js
index ca9738fe78..7568a1b6da 100644
--- a/api/server/controllers/mcpApps.js
+++ b/api/server/controllers/mcpApps.js
@@ -17,8 +17,11 @@ const readMCPResource = async (req, res) => {
     if (!serverName || !uri) {
       return res.status(400).json({ error: 'serverName and uri are required' });
     }
-    if (typeof uri !== 'string' || !uri.startsWith('ui://')) {
-      return res.status(400).json({ error: 'uri must use the ui:// scheme' });
+    // The serverResources capability lets an app read any resource the connected MCP server
+    // exposes (ui:// templates plus supporting data such as file:// or custom schemes), so the
+    // proxy only requires a non-empty string and leaves resource authorization to the server.
+    if (typeof uri !== 'string' || uri.length === 0) {
+      return res.status(400).json({ error: 'uri must be a non-empty string' });
     }
 
     const mcpManager = getMCPManager();
diff --git a/client/public/mcp-sandbox.html b/client/public/mcp-sandbox.html
index a6e87b0122..f2e5483dab 100644
--- a/client/public/mcp-sandbox.html
+++ b/client/public/mcp-sandbox.html
@@ -167,9 +167,9 @@
       ].join('; ');
     }
 
-    // Only permit host patterns: optional scheme, optional wildcard subdomain prefix,
-    // hostname characters, optional port. Rejects CSP keywords and injection attempts.
-    const SAFE_HOST_RE = /^(?:https?:\/\/)?(?:\*\.)?[a-zA-Z0-9][a-zA-Z0-9\-.]*(?::\d{1,5})?$/;
+    // Only permit host patterns: optional http(s)/ws(s) scheme, optional wildcard subdomain
+    // prefix, hostname characters, optional port. Rejects CSP keywords and injection attempts.
+    const SAFE_HOST_RE = /^(?:(?:https?|wss?):\/\/)?(?:\*\.)?[a-zA-Z0-9][a-zA-Z0-9\-.]*(?::\d{1,5})?$/;
 
     function toDomainList(value) {
       if (!Array.isArray(value)) return '';
diff --git a/client/src/components/Chat/Messages/Content/ToolCall.tsx b/client/src/components/Chat/Messages/Content/ToolCall.tsx
index ba134f96c7..a5c6b96e6e 100644
--- a/client/src/components/Chat/Messages/Content/ToolCall.tsx
+++ b/client/src/components/Chat/Messages/Content/ToolCall.tsx
@@ -10,10 +10,10 @@ import {
   actionDomainSeparator,
 } from 'librechat-data-provider';
 import type { TAttachment, UIResource } from 'librechat-data-provider';
+import { getMCPSandboxUrl, buildAppToolResult } from '~/utils/mcpApps';
 import { useLocalize, useProgress, useExpandCollapse } from '~/hooks';
 import { ToolIcon, getToolIconType, isError } from './ToolOutput';
 import { useMCPIconMap, useAppBridge } from '~/hooks/MCP';
-import { getMCPSandboxUrl } from '~/utils/mcpApps';
 import { AttachmentGroup } from './Parts';
 import ToolCallInfo from './ToolCallInfo';
 import ProgressText from './ProgressText';
@@ -50,17 +50,7 @@ const MCPAppView = React.memo(function MCPAppView({
     }
   }, [args]);
 
-  const toolResult = useMemo(() => {
-    const sc = app.structuredContent as Record<string, unknown> | undefined | null;
-    const content = (app.content as [] | undefined) ?? [];
-    if ((!sc || typeof sc !== 'object' || Array.isArray(sc)) && content.length === 0)
-      return undefined;
-    return {
-      content,
-      ...(sc && typeof sc === 'object' && !Array.isArray(sc) ? { structuredContent: sc } : {}),
-      ...(app.isError === true ? { isError: true } : {}),
-    };
-  }, [app.structuredContent, app.content, app.isError]);
+  const toolResult = useMemo(() => buildAppToolResult(app), [app]);
 
   const handleSizeChanged = useCallback((params: { height?: number; width?: number }) => {
     if (params.height && params.height > 0) {
@@ -71,7 +61,8 @@ const MCPAppView = React.memo(function MCPAppView({
 
   useAppBridge(iframeRef, app, toolArgs, toolResult, handleSizeChanged);
 
-  if (app.text && (app.mimeType ?? 'text/html').includes('html')) {
+  const isAppBacked = !!(app.toolName && app.serverName);
+  if (!isAppBacked && app.text && (app.mimeType ?? 'text/html').includes('html')) {
     return (
       <div className="my-2">
         <iframe
diff --git a/client/src/components/Chat/Messages/Content/UIResourceCarousel.tsx b/client/src/components/Chat/Messages/Content/UIResourceCarousel.tsx
index 1e67b52c12..637fa54188 100644
--- a/client/src/components/Chat/Messages/Content/UIResourceCarousel.tsx
+++ b/client/src/components/Chat/Messages/Content/UIResourceCarousel.tsx
@@ -1,6 +1,6 @@
 import React, { useState } from 'react';
 import type { UIResource } from 'librechat-data-provider';
-import { getMCPSandboxUrl } from '~/utils/mcpApps';
+import { getMCPSandboxUrl, buildAppToolResult } from '~/utils/mcpApps';
 import { useAppBridge } from '~/hooks/MCP';
 import { useLocalize } from '~/hooks';
 
@@ -20,17 +20,7 @@ function MCPAppCard({
   const [loaded, setLoaded] = useState(false);
   const sandboxUrl = React.useMemo(() => getMCPSandboxUrl(), []);
 
-  const toolResult = React.useMemo(() => {
-    const sc = resource.structuredContent as Record<string, unknown> | undefined | null;
-    const content = (resource.content as [] | undefined) ?? [];
-    if ((!sc || typeof sc !== 'object' || Array.isArray(sc)) && content.length === 0)
-      return undefined;
-    return {
-      content,
-      ...(sc && typeof sc === 'object' && !Array.isArray(sc) ? { structuredContent: sc } : {}),
-      ...(resource.isError === true ? { isError: true } : {}),
-    };
-  }, [resource.structuredContent, resource.content, resource.isError]);
+  const toolResult = React.useMemo(() => buildAppToolResult(resource), [resource]);
 
   const handleSizeChanged = React.useCallback(
     (params: { height?: number; width?: number }) => {
@@ -50,7 +40,7 @@ function MCPAppCard({
     handleSizeChanged,
   );
 
-  if (resource.toolName && resource.serverName && !resource.text) {
+  if (resource.toolName && resource.serverName) {
     return (
       <>
         {!loaded && (
diff --git a/client/src/components/Chat/Messages/Content/__tests__/Markdown.mcpui.test.tsx b/client/src/components/Chat/Messages/Content/__tests__/Markdown.mcpui.test.tsx
index 63e8c344d6..b0b23b65c0 100644
--- a/client/src/components/Chat/Messages/Content/__tests__/Markdown.mcpui.test.tsx
+++ b/client/src/components/Chat/Messages/Content/__tests__/Markdown.mcpui.test.tsx
@@ -24,6 +24,7 @@ jest.mock('~/hooks');
 jest.mock('~/hooks/Messages/useConversationUIResources');
 
 jest.mock('~/utils/mcpApps', () => ({
+  buildAppToolResult: jest.fn(),
   getMCPSandboxUrl: () => 'http://localhost/sandbox',
   callMCPAppTool: jest.fn(),
   readMCPResource: jest.fn(),
diff --git a/client/src/components/Chat/Messages/Content/__tests__/ToolCall.test.tsx b/client/src/components/Chat/Messages/Content/__tests__/ToolCall.test.tsx
index c519198365..a1f206d079 100644
--- a/client/src/components/Chat/Messages/Content/__tests__/ToolCall.test.tsx
+++ b/client/src/components/Chat/Messages/Content/__tests__/ToolCall.test.tsx
@@ -201,9 +201,10 @@ describe('ToolCall', () => {
         <ToolCall {...mockProps} attachments={attachments as any} />,
       );
 
-      const iframe = container.querySelector('iframe[srcdoc]');
+      // A server-bound inline resource renders through the sandbox bridge (not bare srcDoc),
+      // so its App.connect handshake receives tool input/results.
+      const iframe = container.querySelector('iframe[data-sandbox-url]');
       expect(iframe).toBeInTheDocument();
-      expect(iframe).toHaveAttribute('srcdoc', '<p>inline resource</p>');
     });
   });
 
diff --git a/client/src/components/Chat/Messages/Content/__tests__/UIResourceCarousel.test.tsx b/client/src/components/Chat/Messages/Content/__tests__/UIResourceCarousel.test.tsx
index 082ee66d3d..67c4cb5f3a 100644
--- a/client/src/components/Chat/Messages/Content/__tests__/UIResourceCarousel.test.tsx
+++ b/client/src/components/Chat/Messages/Content/__tests__/UIResourceCarousel.test.tsx
@@ -8,6 +8,7 @@ jest.mock('~/hooks/MCP', () => ({
 }));
 
 jest.mock('~/utils/mcpApps', () => ({
+  buildAppToolResult: jest.fn(),
   getMCPSandboxUrl: () => 'http://localhost/sandbox',
   callMCPAppTool: jest.fn(),
   readMCPResource: jest.fn(),
diff --git a/client/src/components/MCPUIResource/MCPUIResource.tsx b/client/src/components/MCPUIResource/MCPUIResource.tsx
index 9a0cf3d66b..5016a0718b 100644
--- a/client/src/components/MCPUIResource/MCPUIResource.tsx
+++ b/client/src/components/MCPUIResource/MCPUIResource.tsx
@@ -1,7 +1,7 @@
 import React, { useRef, useState, useMemo, useCallback } from 'react';
 import { useConversationUIResources } from '~/hooks/Messages/useConversationUIResources';
+import { getMCPSandboxUrl, buildAppToolResult } from '~/utils/mcpApps';
 import { useOptionalMessagesConversation } from '~/Providers';
-import { getMCPSandboxUrl } from '~/utils/mcpApps';
 import { useAppBridge } from '~/hooks/MCP';
 import { useLocalize } from '~/hooks';
 import { logger } from '~/utils';
@@ -28,17 +28,10 @@ export function MCPUIResource(props: MCPUIResourceProps) {
   const [height, setHeight] = useState<number | undefined>(undefined);
   const sandboxUrl = useMemo(() => getMCPSandboxUrl(), []);
 
-  const toolResult = useMemo(() => {
-    const sc = uiResource?.structuredContent as Record<string, unknown> | undefined | null;
-    const content = (uiResource?.content as [] | undefined) ?? [];
-    if ((!sc || typeof sc !== 'object' || Array.isArray(sc)) && content.length === 0)
-      return undefined;
-    return {
-      content,
-      ...(sc && typeof sc === 'object' && !Array.isArray(sc) ? { structuredContent: sc } : {}),
-      ...(uiResource?.isError === true ? { isError: true } : {}),
-    };
-  }, [uiResource?.structuredContent, uiResource?.content, uiResource?.isError]);
+  const toolResult = useMemo(
+    () => (uiResource ? buildAppToolResult(uiResource) : undefined),
+    [uiResource],
+  );
 
   const handleSizeChanged = useCallback((params: { height?: number; width?: number }) => {
     if (params.height && params.height > 0) {
@@ -66,7 +59,7 @@ export function MCPUIResource(props: MCPUIResourceProps) {
   }
 
   try {
-    if (uiResource.toolName && uiResource.serverName && !uiResource.text) {
+    if (uiResource.toolName && uiResource.serverName) {
       return (
         <span
           className="mx-1 inline-block w-full align-middle"
diff --git a/client/src/components/MCPUIResource/__tests__/MCPUIResource.test.tsx b/client/src/components/MCPUIResource/__tests__/MCPUIResource.test.tsx
index 6ea59b89c9..9556c0fc72 100644
--- a/client/src/components/MCPUIResource/__tests__/MCPUIResource.test.tsx
+++ b/client/src/components/MCPUIResource/__tests__/MCPUIResource.test.tsx
@@ -19,6 +19,7 @@ jest.mock('~/hooks/MCP', () => ({
 }));
 
 jest.mock('~/utils/mcpApps', () => ({
+  buildAppToolResult: jest.fn(),
   getMCPSandboxUrl: () => 'http://localhost/sandbox',
   callMCPAppTool: jest.fn(),
   readMCPResource: jest.fn(),
diff --git a/client/src/hooks/MCP/useAppBridge.ts b/client/src/hooks/MCP/useAppBridge.ts
index 43b8ca695c..bee136a589 100644
--- a/client/src/hooks/MCP/useAppBridge.ts
+++ b/client/src/hooks/MCP/useAppBridge.ts
@@ -6,6 +6,7 @@ import {
   buildAllowAttribute,
 } from '@modelcontextprotocol/ext-apps/app-bridge';
 import type { UIResource } from 'librechat-data-provider';
+import type { AppToolResult } from '~/utils/mcpApps';
 import { callMCPAppTool, fetchMCPResourceHtml, readMCPResource } from '~/utils/mcpApps';
 import { useOptionalMessagesOperations } from '~/Providers';
 import { logger } from '~/utils';
@@ -19,7 +20,7 @@ export function useAppBridge(
   iframeRef: React.RefObject<HTMLIFrameElement | null>,
   resource: UIResource,
   toolArgs: Record<string, unknown> | undefined,
-  toolResult: { content: []; structuredContent?: Record<string, unknown> } | undefined,
+  toolResult: AppToolResult | undefined,
   onSizeChanged: (params: SizeParams) => void,
 ) {
   const user = useRecoilValue(store.user);
@@ -64,7 +65,13 @@ export function useAppBridge(
       bridge = new AppBridge(
         null,
         { name: 'LibreChat', version: '1.0.0' },
-        { openLinks: {}, serverTools: {}, serverResources: {}, logging: {} },
+        {
+          openLinks: {},
+          serverTools: {},
+          serverResources: {},
+          logging: {},
+          message: { text: {} },
+        },
         {
           hostContext: {
             theme,
@@ -114,11 +121,11 @@ export function useAppBridge(
 
       bridge.addEventListener('sandboxready', async () => {
         try {
-          const { html, csp, permissions } = await fetchMCPResourceHtml(
-            resource.serverName as string,
-            resource.uri,
-            user?.id,
-          );
+          // Inline mcp-app resources already carry their HTML, so use it directly instead of a
+          // resources/read round trip; resourceUri-only apps are fetched from the server.
+          const { html, csp, permissions } = resource.text
+            ? { html: resource.text, csp: resource.csp, permissions: resource.permissions }
+            : await fetchMCPResourceHtml(resource.serverName as string, resource.uri, user?.id);
           const resolvedPermissions = permissions ?? resource.permissions;
           if (resolvedPermissions) {
             const updatedAllow = buildAllowAttribute(
diff --git a/client/src/utils/mcpApps.ts b/client/src/utils/mcpApps.ts
index 1efe5f166c..c4732fbac6 100644
--- a/client/src/utils/mcpApps.ts
+++ b/client/src/utils/mcpApps.ts
@@ -1,4 +1,40 @@
 import { request, apiBaseUrl } from 'librechat-data-provider';
+import type { UIResource } from 'librechat-data-provider';
+
+export type AppToolResult = {
+  content: [];
+  structuredContent?: Record<string, unknown>;
+  isError?: boolean;
+  _meta?: Record<string, unknown>;
+};
+
+/**
+ * Builds the App Bridge tool result from a UI resource. App-backed resources (toolName +
+ * serverName) always produce a result so the app's ontoolresult fires even for empty output,
+ * and the tool result's _meta is forwarded for apps that hydrate from it.
+ */
+export function buildAppToolResult(resource: UIResource): AppToolResult | undefined {
+  const sc = resource.structuredContent as Record<string, unknown> | undefined | null;
+  const content = (resource.content as [] | undefined) ?? [];
+  const meta = resource.resultMeta as Record<string, unknown> | undefined;
+  const hasStructured = !!sc && typeof sc === 'object' && !Array.isArray(sc);
+  const isAppBacked = !!(resource.toolName && resource.serverName);
+  if (
+    !hasStructured &&
+    content.length === 0 &&
+    meta == null &&
+    resource.isError !== true &&
+    !isAppBacked
+  ) {
+    return undefined;
+  }
+  return {
+    content,
+    ...(hasStructured ? { structuredContent: sc } : {}),
+    ...(resource.isError === true ? { isError: true } : {}),
+    ...(meta != null ? { _meta: meta } : {}),
+  };
+}
 
 export function getMCPSandboxUrl(): string {
   const configured = (import.meta.env as Record<string, string | undefined>).VITE_MCP_SANDBOX_URL;
diff --git a/packages/api/src/mcp/MCPManager.ts b/packages/api/src/mcp/MCPManager.ts
index dca4ee2fd3..ae2772bc57 100644
--- a/packages/api/src/mcp/MCPManager.ts
+++ b/packages/api/src/mcp/MCPManager.ts
@@ -70,6 +70,8 @@ export class MCPManager extends UserConnectionManager {
 
   private readonly modelOnlyToolCache = new Map<string, Set<string>>();
   private readonly knownToolNamesCache = new Map<string, Set<string>>();
+  /** createdAt of the connection each cache entry was built from, to detect reconnects. */
+  private readonly toolCacheConnStamp = new Map<string, number>();
 
   /** Creates and initializes the singleton MCPManager instance */
   public static async createInstance(configs: t.MCPServers): Promise<MCPManager> {
@@ -354,6 +356,7 @@ Please follow these instructions when using tools from the respective MCP server
       this.resourceUriCache.delete(cacheKey);
       this.modelOnlyToolCache.delete(cacheKey);
       this.knownToolNamesCache.delete(cacheKey);
+      this.toolCacheConnStamp.delete(cacheKey);
       return;
     }
     if (serverName) {
@@ -362,15 +365,29 @@ Please follow these instructions when using tools from the respective MCP server
           this.resourceUriCache.delete(key);
           this.modelOnlyToolCache.delete(key);
           this.knownToolNamesCache.delete(key);
+          this.toolCacheConnStamp.delete(key);
         }
       }
     } else {
       this.resourceUriCache.clear();
       this.modelOnlyToolCache.clear();
       this.knownToolNamesCache.clear();
+      this.toolCacheConnStamp.clear();
     }
   }
 
+  /**
+   * App-level connections can be transparently recreated when a server config changes
+   * (ConnectionsRepository.get), so cached tool metadata is only valid while it was built
+   * from the current connection instance.
+   */
+  private isToolCacheFresh(cacheKey: string, connection: MCPConnection): boolean {
+    return (
+      this.knownToolNamesCache.has(cacheKey) &&
+      this.toolCacheConnStamp.get(cacheKey) === connection.createdAt
+    );
+  }
+
   protected removeUserConnection(userId: string, serverName: string): void {
     this.clearResourceUriCache(serverName, userId);
     super.removeUserConnection(userId, serverName);
@@ -412,6 +429,7 @@ Please follow these instructions when using tools from the respective MCP server
     this.resourceUriCache.set(cacheKey, serverMap);
     this.modelOnlyToolCache.set(cacheKey, modelOnly);
     this.knownToolNamesCache.set(cacheKey, knownNames);
+    this.toolCacheConnStamp.set(cacheKey, connection.createdAt);
   }
 
   private async getResourceMeta(
@@ -430,7 +448,7 @@ Please follow these instructions when using tools from the respective MCP server
       return serverMap.get(toolName);
     }
     const cacheKey = `${serverName}:${userId ?? ''}`;
-    if (!this.resourceUriCache.has(cacheKey)) {
+    if (!this.isToolCacheFresh(cacheKey, connection)) {
       await this.populateToolCaches(connection, cacheKey);
     }
     return this.resourceUriCache.get(cacheKey)?.get(toolName);
@@ -817,7 +835,7 @@ Please follow these instructions when using tools from the respective MCP server
     }
 
     const cacheKey = `${serverName}:${userId ?? ''}`;
-    if (!this.knownToolNamesCache.has(cacheKey)) {
+    if (!this.isToolCacheFresh(cacheKey, connection)) {
       await this.populateToolCaches(connection, cacheKey);
     }
     if (!this.knownToolNamesCache.get(cacheKey)?.has(toolName)) {
diff --git a/packages/api/src/mcp/parsers.ts b/packages/api/src/mcp/parsers.ts
index 942cb096ac..2d13a2d1b4 100644
--- a/packages/api/src/mcp/parsers.ts
+++ b/packages/api/src/mcp/parsers.ts
@@ -210,6 +210,7 @@ export function formatToolContent(
           structuredContent: result?.structuredContent,
           content: result?.content,
           isError: result?.isError,
+          resultMeta: (result as { _meta?: Record<string, unknown> })?._meta,
           csp: metadata?.csp,
           permissions: metadata?.permissions,
           toolArgs: metadata?.toolArgs,
@@ -267,6 +268,7 @@ export function formatToolContent(
       permissions: metadata.permissions,
       toolArgs: metadata.toolArgs,
       isError: result?.isError,
+      resultMeta: (result as { _meta?: Record<string, unknown> })?._meta,
     });
     currentTextBlock +=
       (currentTextBlock ? '\n\n' : '') +
diff --git a/packages/data-provider/src/schemas.ts b/packages/data-provider/src/schemas.ts
index 9e3de6d091..c5129a5cd5 100644
--- a/packages/data-provider/src/schemas.ts
+++ b/packages/data-provider/src/schemas.ts
@@ -854,6 +854,7 @@ export type UIResource = {
   };
   toolArgs?: Record<string, unknown>;
   isError?: boolean;
+  resultMeta?: Record<string, unknown>;
   [key: string]: unknown;
 };