diff --git a/x-pack/platform/test/api_integration_deployment_agnostic/default_configs/serverless.config.base.ts b/x-pack/platform/test/api_integration_deployment_agnostic/default_configs/serverless.config.base.ts
index 4480514106fd4..4ca4af63478eb 100644
--- a/x-pack/platform/test/api_integration_deployment_agnostic/default_configs/serverless.config.base.ts
+++ b/x-pack/platform/test/api_integration_deployment_agnostic/default_configs/serverless.config.base.ts
@@ -25,8 +25,13 @@ interface CreateTestConfigOptions<T> {
   indexRefreshInterval?: string | false;
 }
 
-// include settings from elasticsearch controller
+// These args replicate the MKI setup from the elasticsearch controller:
 // https://github.com/elastic/elasticsearch-controller/blob/main/helm/values.yaml
+//
+// ⚠️  Tests targeting these configs run against MKI. Adding a server arg here may allow
+//     tests to pass on Kibana CI but will cause failures on MKI if it is not yet supported there.
+//     If your test needs a feature flag, create a config under feature_flag_configs/ using
+//     createServerlessFeatureFlagTestConfig from feature_flag.serverless.config.base.ts.
 const esServerArgsFromController = {
   es: [],
   oblt: ['xpack.apm_data.enabled=true'],
@@ -34,8 +39,13 @@ const esServerArgsFromController = {
   workplaceai: [],
 };
 
-// include settings from kibana controller
+// These args replicate the MKI setup from the kibana controller:
 // https://github.com/elastic/kibana-controller/blob/main/internal/controllers/kibana/config/config_settings.go
+//
+// ⚠️  Tests targeting these configs run against MKI. Adding a server arg here may allow
+//     tests to pass on Kibana CI but will cause failures on MKI if it is not yet supported there.
+//     If your test needs a feature flag, create a config under feature_flag_configs/ using
+//     createServerlessFeatureFlagTestConfig from feature_flag.serverless.config.base.ts.
 const kbnServerArgsFromController = {
   es: [
     // useful for testing (also enabled in MKI QA)
@@ -60,8 +70,10 @@ export function createServerlessTestConfig<T extends DeploymentAgnosticCommonSer
   return async ({ readConfigFile }: FtrConfigProviderContext): Promise<Config> => {
     if (options.esServerArgs || options.kbnServerArgs) {
       throw new Error(
-        `FTR doesn't provision custom ES/Kibana server arguments into the serverless project on MKI.
-  It may lead to unexpected test failures on Cloud. Please contact #appex-qa.`
+        `Deployment-agnostic configs run unchanged on MKI. Custom ES/Kibana server args passed here
+  won't be set on MKI and will cause unexpected test failures on Cloud.
+  If your test needs a feature flag, create a config under feature_flag_configs/ using
+  createServerlessFeatureFlagTestConfig from feature_flag.serverless.config.base.ts.`
       );
     }
 
diff --git a/x-pack/platform/test/api_integration_deployment_agnostic/default_configs/stateful.config.base.ts b/x-pack/platform/test/api_integration_deployment_agnostic/default_configs/stateful.config.base.ts
index 4f05c220ea172..a73030253511c 100644
--- a/x-pack/platform/test/api_integration_deployment_agnostic/default_configs/stateful.config.base.ts
+++ b/x-pack/platform/test/api_integration_deployment_agnostic/default_configs/stateful.config.base.ts
@@ -49,8 +49,10 @@ export function createStatefulTestConfig<T extends DeploymentAgnosticCommonServi
   return async ({ readConfigFile }: FtrConfigProviderContext) => {
     if (options.esServerArgs || options.kbnServerArgs) {
       throw new Error(
-        `FTR doesn't provision custom ES/Kibana server arguments into the ESS deployment.
-  It may lead to unexpected test failures on Cloud. Please contact #appex-qa.`
+        `Deployment-agnostic configs run unchanged on ECH (Elastic Cloud). Custom ES/Kibana server args passed here
+  won't be set on ECH and will cause unexpected test failures.
+  If your test needs a feature flag, create a config under feature_flag_configs/ using
+  createStatefulFeatureFlagTestConfig from feature_flag.stateful.config.base.ts.`
       );
     }
 
@@ -99,6 +101,8 @@ export function createStatefulTestConfig<T extends DeploymentAgnosticCommonServi
         exclude: [...(options.suiteTags?.exclude || []), 'skipStateful'],
       },
 
+      // ⚠️  Do not add server args here to make tests pass as they won't be set on ECH (Elastic Cloud Hosted).
+      //     If your test needs a feature flag, use createStatefulFeatureFlagTestConfig (feature_flag_configs/).
       esTestCluster: {
         ...xPackAPITestsConfig.get('esTestCluster'),
         serverArgs: [
@@ -123,6 +127,8 @@ export function createStatefulTestConfig<T extends DeploymentAgnosticCommonServi
           path.resolve(REPO_ROOT, STATEFUL_ROLES_ROOT_PATH, 'roles.yml'),
         ],
       },
+      // ⚠️  Do not add server args here to make tests pass as they won't be set on ECH (Elastic Cloud Hosted).
+      //     If your test needs a feature flag, use createStatefulFeatureFlagTestConfig (feature_flag_configs/).
       kbnTestServer: {
         ...xPackAPITestsConfig.get('kbnTestServer'),
         serverArgs: [