diff --git a/frontend/src/components/thread/tool-views/expand-message-tool/ExpandMessageToolView.tsx b/frontend/src/components/thread/tool-views/expand-message-tool/ExpandMessageToolView.tsx
new file mode 100644
index 00000000..3743c67b
--- /dev/null
+++ b/frontend/src/components/thread/tool-views/expand-message-tool/ExpandMessageToolView.tsx
@@ -0,0 +1,175 @@
+import React from 'react';
+import {
+  Expand,
+  CheckCircle,
+  AlertTriangle,
+  Loader2,
+  Clock,
+  MessageSquareText,
+  Copy,
+  Check,
+} from 'lucide-react';
+import { ToolViewProps } from '../types';
+import { formatTimestamp, getToolTitle } from '../utils';
+import { extractExpandMessageData } from './_utils';
+import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
+import { Badge } from '@/components/ui/badge';
+import { ScrollArea } from "@/components/ui/scroll-area";
+import { Button } from '@/components/ui/button';
+import { toast } from 'sonner';
+import Markdown from 'react-markdown';
+
+export function ExpandMessageToolView({
+  name = 'expand_message',
+  assistantContent,
+  toolContent,
+  assistantTimestamp,
+  toolTimestamp,
+  isSuccess = true,
+  isStreaming = false,
+}: ToolViewProps) {
+  const {
+    messageId,
+    message,
+    status,
+    actualIsSuccess,
+    actualToolTimestamp,
+    actualAssistantTimestamp
+  } = extractExpandMessageData(
+    assistantContent,
+    toolContent,
+    isSuccess,
+    toolTimestamp,
+    assistantTimestamp
+  );
+
+  const [isCopying, setIsCopying] = React.useState(false);
+  const toolTitle = getToolTitle(name) || 'Message Expansion';
+
+  const copyToClipboard = React.useCallback(async (text: string) => {
+    try {
+      await navigator.clipboard.writeText(text);
+      return true;
+    } catch (err) {
+      console.error('Failed to copy text: ', err);
+      return false;
+    }
+  }, []);
+
+  const handleCopyMessage = React.useCallback(async () => {
+    if (!message) return;
+
+    setIsCopying(true);
+    const success = await copyToClipboard(message);
+    if (success) {
+      toast.success('Message copied to clipboard');
+    } else {
+      toast.error('Failed to copy message');
+    }
+    setTimeout(() => setIsCopying(false), 500);
+  }, [message, copyToClipboard]);
+
+  return (
+    <Card className="gap-0 flex border shadow-none border-t border-b-0 border-x-0 p-0 rounded-none flex-col h-full overflow-hidden bg-card">
+      <CardHeader className="h-14 bg-zinc-50/80 dark:bg-zinc-900/80 backdrop-blur-sm border-b p-2 px-4 space-y-2">
+        <div className="flex flex-row items-center justify-between">
+          <div className="flex items-center gap-2">
+            <div className="relative p-2 rounded-xl bg-gradient-to-br from-purple-500/20 to-purple-600/10 border border-purple-500/20">
+              <Expand className="w-5 h-5 text-purple-500 dark:text-purple-400" />
+            </div>
+            <div>
+              <CardTitle className="text-base font-medium text-zinc-900 dark:text-zinc-100">
+                {toolTitle}
+              </CardTitle>
+            </div>
+          </div>
+
+          {!isStreaming && (
+            <Badge
+              variant="secondary"
+              className={
+                actualIsSuccess
+                  ? "bg-gradient-to-b from-emerald-200 to-emerald-100 text-emerald-700 dark:from-emerald-800/50 dark:to-emerald-900/60 dark:text-emerald-300"
+                  : "bg-gradient-to-b from-rose-200 to-rose-100 text-rose-700 dark:from-rose-800/50 dark:to-rose-900/60 dark:text-rose-300"
+              }
+            >
+              {actualIsSuccess ? (
+                <CheckCircle className="h-3.5 w-3.5 mr-1" />
+              ) : (
+                <AlertTriangle className="h-3.5 w-3.5 mr-1" />
+              )}
+              {actualIsSuccess ? 'Expanded' : 'Failed'}
+            </Badge>
+          )}
+
+          {isStreaming && (
+            <Badge className="bg-gradient-to-b from-purple-200 to-purple-100 text-purple-700 dark:from-purple-800/50 dark:to-purple-900/60 dark:text-purple-300">
+              <Loader2 className="h-3.5 w-3.5 animate-spin mr-1" />
+              Expanding
+            </Badge>
+          )}
+        </div>
+      </CardHeader>
+
+      <CardContent className="p-0 flex-1 overflow-hidden relative">
+        <ScrollArea className="h-full w-full">
+          <div className="p-4 space-y-4">
+            {/* Message ID */}
+            {messageId && (
+              <div className="flex items-center gap-2">
+                <Badge 
+                  variant="outline" 
+                  className="font-mono text-xs bg-purple-50 dark:bg-purple-950/20 border-purple-200 dark:border-purple-800"
+                >
+                  ID: {messageId}
+                </Badge>
+              </div>
+            )}
+
+            {/* Expanded Message Content - Simple display */}
+            {message ? (
+              <div className="bg-muted/30 rounded-lg p-4 border border-border overflow-hidden">
+                <div className="prose prose-sm dark:prose-invert chat-markdown max-w-none [&>:first-child]:mt-0 break-words overflow-wrap-anywhere [&_pre]:whitespace-pre-wrap [&_pre]:break-words [&_code]:break-words">
+                  <Markdown>{message}</Markdown>
+                </div>
+              </div>
+            ) : !isStreaming ? (
+              <div className="flex flex-col items-center justify-center py-12 text-center">
+                <div className="w-16 h-16 rounded-full bg-purple-100 dark:bg-purple-900/20 flex items-center justify-center mb-4 border-2 border-purple-200 dark:border-purple-800">
+                  <MessageSquareText className="h-8 w-8 text-purple-500 dark:text-purple-400" />
+                </div>
+                <h3 className="text-lg font-medium text-foreground mb-2">
+                  {actualIsSuccess ? 'No Message Content' : 'Expansion Failed'}
+                </h3>
+                <p className="text-sm text-muted-foreground max-w-md">
+                  {actualIsSuccess 
+                    ? 'The expanded message does not contain any displayable content.'
+                    : 'Unable to expand the requested message. It may not exist or you may not have access to it.'}
+                </p>
+              </div>
+            ) : null}
+          </div>
+        </ScrollArea>
+      </CardContent>
+
+      <div className="px-4 py-2 h-10 backdrop-blur-sm border-t border-purple-200 dark:border-purple-800 flex justify-between items-center gap-4">
+        <div className="h-full flex items-center gap-2 text-sm text-purple-600 dark:text-purple-400">
+          <Badge className="h-6 py-0.5 bg-purple-100 dark:bg-purple-900/30 text-purple-700 dark:text-purple-300 border-purple-200 dark:border-purple-800" variant="outline">
+            <Expand className="h-3 w-3 mr-1" />
+            Message Retrieval
+          </Badge>
+        </div>
+
+        <div className="text-xs text-zinc-500 dark:text-zinc-400 flex items-center gap-1.5">
+          <Clock className="h-3.5 w-3.5" />
+          {actualToolTimestamp 
+            ? formatTimestamp(actualToolTimestamp) 
+            : actualAssistantTimestamp 
+            ? formatTimestamp(actualAssistantTimestamp) 
+            : ''}
+        </div>
+      </div>
+    </Card>
+  );
+}
+
diff --git a/frontend/src/components/thread/tool-views/expand-message-tool/_utils.ts b/frontend/src/components/thread/tool-views/expand-message-tool/_utils.ts
new file mode 100644
index 00000000..7762979d
--- /dev/null
+++ b/frontend/src/components/thread/tool-views/expand-message-tool/_utils.ts
@@ -0,0 +1,161 @@
+import { extractToolData } from '../utils';
+
+export interface ExpandMessageData {
+  messageId?: string;
+  message?: string;
+  status?: string;
+  actualIsSuccess: boolean;
+  actualToolTimestamp?: string;
+  actualAssistantTimestamp?: string;
+}
+
+const parseContent = (content: any): any => {
+  if (typeof content === 'string') {
+    try {
+      return JSON.parse(content);
+    } catch (e) {
+      return content;
+    }
+  }
+  return content;
+};
+
+const extractFromNewFormat = (content: any): {
+  messageId?: string;
+  message?: string;
+  status?: string;
+  success?: boolean;
+  timestamp?: string;
+} => {
+  const parsedContent = parseContent(content);
+  
+  if (!parsedContent || typeof parsedContent !== 'object') {
+    return {};
+  }
+
+  // Handle new format with tool_execution
+  if ('tool_execution' in parsedContent && typeof parsedContent.tool_execution === 'object') {
+    const toolExecution = parsedContent.tool_execution;
+    const args = toolExecution.arguments || {};
+    
+    let parsedOutput = toolExecution.result?.output;
+    if (typeof parsedOutput === 'string') {
+      try {
+        parsedOutput = JSON.parse(parsedOutput);
+      } catch (e) {
+        // Keep as string
+      }
+    }
+
+    const extractedData: any = {
+      messageId: args.message_id,
+      success: toolExecution.result?.success,
+      timestamp: toolExecution.execution_details?.timestamp
+    };
+
+    // Extract message and status from output
+    if (parsedOutput && typeof parsedOutput === 'object') {
+      extractedData.status = parsedOutput.status;
+      extractedData.message = parsedOutput.message || parsedOutput.content;
+    } else if (typeof parsedOutput === 'string') {
+      extractedData.message = parsedOutput;
+    }
+    
+    return extractedData;
+  }
+
+  // Handle content wrapper
+  if ('role' in parsedContent && 'content' in parsedContent) {
+    return extractFromNewFormat(parsedContent.content);
+  }
+
+  return {};
+};
+
+const extractFromLegacyFormat = (content: any): {
+  messageId?: string;
+  message?: string;
+  status?: string;
+} => {
+  const toolData = extractToolData(content);
+  
+  if (toolData.arguments || toolData.toolResult) {
+    const result: any = {
+      messageId: toolData.arguments?.message_id
+    };
+
+    const output = toolData.toolResult?.toolOutput;
+    if (output) {
+      if (typeof output === 'object' && output !== null) {
+        result.status = (output as any).status;
+        result.message = (output as any).message || (output as any).content;
+      } else if (typeof output === 'string') {
+        try {
+          const parsed = JSON.parse(output);
+          result.status = parsed.status;
+          result.message = parsed.message || parsed.content;
+        } catch {
+          result.message = output;
+        }
+      }
+    }
+    
+    return result;
+  }
+
+  return {};
+};
+
+export function extractExpandMessageData(
+  assistantContent: any,
+  toolContent: any,
+  isSuccess: boolean,
+  toolTimestamp?: string,
+  assistantTimestamp?: string
+): ExpandMessageData {
+  let messageId: string | undefined;
+  let message: string | undefined;
+  let status: string | undefined;
+  let actualIsSuccess = isSuccess;
+  let actualToolTimestamp = toolTimestamp;
+  const actualAssistantTimestamp = assistantTimestamp;
+
+  // Try new format first
+  const assistantNewFormat = extractFromNewFormat(assistantContent);
+  const toolNewFormat = extractFromNewFormat(toolContent);
+
+  // Extract from assistant content (parameters)
+  if (assistantNewFormat.messageId) {
+    messageId = assistantNewFormat.messageId;
+  }
+
+  // Extract from tool result (output)
+  if (toolNewFormat.message || toolNewFormat.status) {
+    message = toolNewFormat.message;
+    status = toolNewFormat.status;
+    if (toolNewFormat.success !== undefined) {
+      actualIsSuccess = toolNewFormat.success;
+    }
+    if (toolNewFormat.timestamp) {
+      actualToolTimestamp = toolNewFormat.timestamp;
+    }
+  } else {
+    // Try legacy format
+    const assistantLegacy = extractFromLegacyFormat(assistantContent);
+    const toolLegacy = extractFromLegacyFormat(toolContent);
+
+    messageId = messageId || assistantLegacy.messageId || toolLegacy.messageId;
+    message = toolLegacy.message;
+    status = toolLegacy.status;
+  }
+
+  return {
+    messageId,
+    message,
+    status,
+    actualIsSuccess,
+    actualToolTimestamp,
+    actualAssistantTimestamp
+  };
+}
+
diff --git a/frontend/src/components/thread/tool-views/wrapper/ToolViewRegistry.tsx b/frontend/src/components/thread/tool-views/wrapper/ToolViewRegistry.tsx
index 8b27e89a..3d03892d 100644
--- a/frontend/src/components/thread/tool-views/wrapper/ToolViewRegistry.tsx
+++ b/frontend/src/components/thread/tool-views/wrapper/ToolViewRegistry.tsx
@@ -58,6 +58,7 @@ import ListAgentWorkflowsToolView from '../list-agent-workflows/list-agent-workf
 import { createPresentationViewerToolContent, parsePresentationSlidePath } from '../utils/presentation-utils';
 import { extractToolData } from '../utils';
 import { KbToolView } from '../KbToolView';
+import { ExpandMessageToolView } from '../expand-message-tool/ExpandMessageToolView';
 
 
 export type ToolViewComponent = React.ComponentType<ToolViewProps>;
@@ -122,6 +123,8 @@ const defaultRegistry: ToolViewRegistryType = {
   'ask': AskToolView,
   'complete': CompleteToolView,
   'wait': WaitToolView,
+  'expand_message': ExpandMessageToolView,
+  'expand-message': ExpandMessageToolView,
 
   'deploy': DeployToolView,