diff --git a/src/tools/emails.ts b/src/tools/emails.ts
index 3308ca7..f8bcfe0 100644
--- a/src/tools/emails.ts
+++ b/src/tools/emails.ts
@@ -149,10 +149,10 @@ export function addEmailTools(
         ...(replierEmailAddresses.length === 0
           ? {
               replyTo: z
-                .array(z.email())
+                .array(z.string())
                 .optional()
                 .describe(
-                  'Optional email addresses for the email readers to reply to. You MUST ask the user for this parameter. Under no circumstance provide it yourself',
+                  'Optional email addresses for the email readers to reply to (e.g. "support@example.com" or "Support Team <support@example.com>"). You MUST ask the user for this parameter. Under no circumstance provide it yourself',
                 ),
             }
           : {}),
@@ -1005,9 +1005,11 @@ export function addEmailTools(
                   'Sender email address. Falls back to the configured default sender if not provided.',
                 ),
               replyTo: z
-                .array(z.email())
+                .array(z.string())
                 .optional()
-                .describe('Reply-to email addresses'),
+                .describe(
+                  'Reply-to email addresses (e.g. "support@example.com" or "Support Team <support@example.com>")',
+                ),
               cc: z.array(z.email()).optional().describe('CC email addresses'),
               bcc: z
                 .array(z.email())
diff --git a/tests/tools/emails.test.ts b/tests/tools/emails.test.ts
index 94888dc..7974005 100644
--- a/tests/tools/emails.test.ts
+++ b/tests/tools/emails.test.ts
@@ -89,6 +89,70 @@ describe('send-email from address format', () => {
   });
 });
 
+describe('replyTo address format', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    send.mockResolvedValue({
+      data: { id: 'email_1' },
+      error: null,
+    });
+    batchSend.mockResolvedValue({
+      data: { data: [{ id: 'email_1' }] },
+      error: null,
+    });
+  });
+
+  it.each([
+    'support@example.com',
+    'Support Team <support@example.com>',
+  ])('passes replyTo through send-email: %s', async (replyTo) => {
+    const client = await makeClient();
+    const result = await client.callTool({
+      name: 'send-email',
+      arguments: {
+        from: 'onboarding@resend.dev',
+        to: ['delivered@resend.dev'],
+        replyTo: [replyTo],
+        subject: 'hello',
+        text: 'world',
+      },
+    });
+
+    expect(result.isError).toBeFalsy();
+    expect(send).toHaveBeenCalledWith(
+      expect.objectContaining({ replyTo: [replyTo] }),
+      undefined,
+    );
+  });
+
+  it.each([
+    'support@example.com',
+    'Support Team <support@example.com>',
+  ])('passes replyTo through send-batch-emails: %s', async (replyTo) => {
+    const client = await makeClient();
+    const result = await client.callTool({
+      name: 'send-batch-emails',
+      arguments: {
+        emails: [
+          {
+            from: 'onboarding@resend.dev',
+            to: ['delivered@resend.dev'],
+            replyTo: [replyTo],
+            subject: 'hello',
+            text: 'world',
+          },
+        ],
+      },
+    });
+
+    expect(result.isError).toBeFalsy();
+    expect(batchSend).toHaveBeenCalledWith(
+      [expect.objectContaining({ replyTo: [replyTo] })],
+      undefined,
+    );
+  });
+});
+
 describe('send-email idempotency key', () => {
   beforeEach(() => {
     vi.clearAllMocks();