fix: remove hardcoded destination_type validation that rejected WHATSAPP

The create_adset allowlist only had APP_STORE, DEEPLINK, APP_INSTALL, ON_AD —
blocking valid values like WHATSAPP, MESSENGER, and INSTAGRAM_DIRECT. Meta's
SDK defines 23+ destination types. Let Meta's API handle validation instead.

Author: nictuku

meta_ads_mcp/core/adsets.py

@@ -138,7 +138,9 @@ async def create_adset(
         end_time: End time in ISO 8601 format
         dsa_beneficiary: DSA beneficiary for European compliance
         promoted_object: App config for APP_INSTALLS. Required: application_id, object_store_url.
-        destination_type: Where users go after click (e.g., 'APP_STORE', 'ON_AD').
+        destination_type: Where users go after click. Common values: 'WEBSITE', 'WHATSAPP', 'MESSENGER',
+                         'INSTAGRAM_DIRECT', 'ON_AD', 'APP', 'FACEBOOK', 'SHOP_AUTOMATIC'.
+                         Also supports multi-channel combos like 'MESSAGING_MESSENGER_WHATSAPP'.
         is_dynamic_creative: Enable Dynamic Creative for this ad set.
         access_token: Meta API access token (optional - will use cached token if not provided)
     """
@@ -202,15 +204,12 @@ async def create_adset(
                 "provided_url": store_url
             }, indent=2)
 
-    # Validate destination_type if provided
-    if destination_type:
-        valid_destination_types = ["APP_STORE", "DEEPLINK", "APP_INSTALL", "ON_AD"]
-        if destination_type not in valid_destination_types:
-            return json.dumps({
-                "error": f"Invalid destination_type: {destination_type}",
-                "valid_values": valid_destination_types
-            }, indent=2)
-    
+    # destination_type is passed through to Meta's API without client-side validation.
+    # Meta supports 23+ values (WHATSAPP, MESSENGER, INSTAGRAM_DIRECT, ON_AD, WEBSITE,
+    # APP, FACEBOOK, SHOP_AUTOMATIC, multi-channel MESSAGING_* combos, etc.)
+    # and may add more. Let Meta's API reject invalid values.
+    # See: facebook-python-business-sdk AdSet.DestinationType
+
     # Basic targeting is required if not provided
     if not targeting:
         targeting = {

tests/test_mobile_app_adset_creation.py

@@ -253,27 +253,26 @@ async def test_invalid_promoted_object_missing_store_url(
             assert 'object_store_url' in result_data['error'].lower()
 
     @pytest.mark.asyncio
-    async def test_invalid_destination_type(
+    async def test_invalid_destination_type_passes_through_to_meta(
         self, mock_api_request, mock_auth_manager, valid_mobile_app_params, ios_promoted_object
     ):
-        """Test validation error for invalid destination_type value"""
-        
+        """Test that invalid destination_type is passed through to Meta API (not rejected by middleware).
+
+        Client-side validation was removed because Meta supports 23+ destination_type values
+        and maintaining a hardcoded allowlist caused false rejections (e.g. WHATSAPP).
+        """
+
         result = await create_adset(
             **valid_mobile_app_params,
             promoted_object=ios_promoted_object,
             destination_type="INVALID_TYPE"
         )
-        
-        result_data = json.loads(result)
-        
-        # Should return validation error - check for data wrapper format
-        if "data" in result_data:
-            error_data = json.loads(result_data["data"]) 
-            assert 'error' in error_data
-            assert 'destination_type' in error_data['error'].lower()
-        else:
-            assert 'error' in result_data
-            assert 'destination_type' in result_data['error'].lower()
+
+        # The request should reach the Meta API (mock_api_request should be called)
+        # rather than being rejected by our middleware
+        call_args = mock_api_request.call_args
+        params = call_args[0][2]
+        assert params['destination_type'] == "INVALID_TYPE"
 
     @pytest.mark.asyncio
     async def test_app_installs_requires_promoted_object(