diff --git a/client/src/components/Chat/Messages/Content/ToolCall.tsx b/client/src/components/Chat/Messages/Content/ToolCall.tsx
index f8e83978aa..3325a34b05 100644
--- a/client/src/components/Chat/Messages/Content/ToolCall.tsx
+++ b/client/src/components/Chat/Messages/Content/ToolCall.tsx
@@ -70,6 +70,19 @@ const MCPAppView = React.memo(function MCPAppView({
 
   useAppBridge(iframeRef, app, toolArgs, toolResult, handleSizeChanged);
 
+  if (app.text && (app.mimeType ?? 'text/html').includes('html')) {
+    return (
+      <div className="my-2">
+        <iframe
+          srcDoc={app.text}
+          sandbox="allow-scripts allow-forms"
+          style={{ width: '100%', minHeight: '200px', border: 'none' }}
+          title={app.uri}
+        />
+      </div>
+    );
+  }
+
   return (
     <div className="my-2" style={height ? { height } : { minHeight: 100 }}>
       {!loaded && !timedOut && (
diff --git a/client/src/components/Chat/Messages/Content/UIResourceCarousel.tsx b/client/src/components/Chat/Messages/Content/UIResourceCarousel.tsx
index afa1a0468b..1e67b52c12 100644
--- a/client/src/components/Chat/Messages/Content/UIResourceCarousel.tsx
+++ b/client/src/components/Chat/Messages/Content/UIResourceCarousel.tsx
@@ -50,7 +50,7 @@ function MCPAppCard({
     handleSizeChanged,
   );
 
-  if (resource.toolName && resource.serverName) {
+  if (resource.toolName && resource.serverName && !resource.text) {
     return (
       <>
         {!loaded && (
diff --git a/client/src/utils/mcpApps.ts b/client/src/utils/mcpApps.ts
index b0e884c8f9..6c354f2472 100644
--- a/client/src/utils/mcpApps.ts
+++ b/client/src/utils/mcpApps.ts
@@ -11,7 +11,7 @@ export async function callMCPAppTool(
   toolName: string,
   args: Record<string, unknown>,
 ) {
-  return request.post('/api/mcp/app-tool-call', {
+  return request.post(`${apiBaseUrl()}/api/mcp/app-tool-call`, {
     serverName,
     toolName,
     arguments: args,
@@ -40,7 +40,7 @@ export async function readMCPResource(serverName: string, uri: string, userId?:
     }
   }
 
-  const promise = request.post('/api/mcp/resources/read', { serverName, uri });
+  const promise = request.post(`${apiBaseUrl()}/api/mcp/resources/read`, { serverName, uri });
   resourceCache.set(key, { promise, ts: now });
   promise.catch(() => resourceCache.delete(key));
   return promise;
diff --git a/packages/api/src/mcp/MCPManager.ts b/packages/api/src/mcp/MCPManager.ts
index 61914d8647..da8341b3a8 100644
--- a/packages/api/src/mcp/MCPManager.ts
+++ b/packages/api/src/mcp/MCPManager.ts
@@ -747,14 +747,19 @@ Please follow these instructions when using tools from the respective MCP server
           `${logPrefix} Server "${serverName}" requires Graph API token resolution which is not supported for app tool calls.`,
         );
       }
-      const currentOptions = processMCPEnv({
-        user,
-        dbSourced: isDbSourced,
-        options: rawConfig as t.MCPOptions,
-      });
-      const resolvedHeaders: Record<string, string> =
-        'headers' in currentOptions ? { ...(currentOptions.headers || {}) } : {};
-      connection.setRequestHeaders(resolvedHeaders);
+      // DB-sourced servers have their customUserVars (e.g. {{MCP_API_KEY}}) resolved during
+      // the original callTool setup. Re-processing without customUserVars would overwrite
+      // those resolved headers with unresolved placeholders, so skip for DB-sourced servers.
+      if (!isDbSourced) {
+        const currentOptions = processMCPEnv({
+          user,
+          dbSourced: false,
+          options: rawConfig as t.MCPOptions,
+        });
+        const resolvedHeaders: Record<string, string> =
+          'headers' in currentOptions ? { ...(currentOptions.headers || {}) } : {};
+        connection.setRequestHeaders(resolvedHeaders);
+      }
     }
 
     const result = await connection.client.request(
diff --git a/packages/api/src/mcp/registry/MCPServerInspector.ts b/packages/api/src/mcp/registry/MCPServerInspector.ts
index 4e0b9438e4..03f7e49a97 100644
--- a/packages/api/src/mcp/registry/MCPServerInspector.ts
+++ b/packages/api/src/mcp/registry/MCPServerInspector.ts
@@ -175,6 +175,17 @@ export class MCPServerInspector {
 
     const toolFunctions: t.LCAvailableTools = {};
     tools.forEach((tool) => {
+      const uiMeta = (tool._meta as Record<string, unknown>)?.ui as
+        | Record<string, unknown>
+        | undefined;
+      const visibility = uiMeta?.visibility as string[] | undefined;
+      if (
+        Array.isArray(visibility) &&
+        visibility.includes('app') &&
+        !visibility.includes('model')
+      ) {
+        return;
+      }
       const name = `${tool.name}${Constants.mcp_delimiter}${serverName}`;
       toolFunctions[name] = {
         type: 'function',