diff --git a/lib/inventory/distributed-service/api-feature.nix b/lib/inventory/distributed-service/api-feature.nix
index 095b674bc..1266bb68a 100644
--- a/lib/inventory/distributed-service/api-feature.nix
+++ b/lib/inventory/distributed-service/api-feature.nix
@@ -1,7 +1,7 @@
 # This module enables itself if
 # manifest.features.API = true
 # It converts the roles.interface to a json-schema
-{ clanLib }:
+{ clanLib, attrName }:
 let
   converter = clanLib.jsonschema {
     includeDefaults = true;
@@ -11,38 +11,41 @@ in
 {
   options.result.api = lib.mkOption {
     default = { };
-    type = lib.types.submodule (
-      lib.optionalAttrs config.manifest.features.API {
-        options.schema = lib.mkOption {
-          description = ''
-            The API schema for configuring the service.
+    type = lib.types.submodule ({
+      options.schema = lib.mkOption {
+        description = ''
+          The API schema for configuring the service.
 
-            Each 'role.<name>.interface' is converted to a json-schema.
-            This can be used to generate and type check the API relevant objects.
-          '';
-          defaultText = lib.literalExpression ''
-            {
-              peer = { $schema" = "http://json-schema.org/draft-07/schema#"; ... }
-              commuter = { $schema" = "http://json-schema.org/draft-07/schema#"; ... }
-              distributor = { $schema" = "http://json-schema.org/draft-07/schema#"; ... }
-            }
-          '';
-          default = lib.mapAttrs (_roleName: v: converter.parseModule v.interface) config.roles;
-        };
-      }
-    );
+          Each 'role.<name>.interface' is converted to a json-schema.
+          This can be used to generate and type check the API relevant objects.
+        '';
+        defaultText = lib.literalExpression ''
+          {
+            peer = { $schema" = "http://json-schema.org/draft-07/schema#"; ... }
+            commuter = { $schema" = "http://json-schema.org/draft-07/schema#"; ... }
+            distributor = { $schema" = "http://json-schema.org/draft-07/schema#"; ... }
+          }
+        '';
+        default = lib.mapAttrs (_roleName: v: converter.parseModule v.interface) config.roles;
+      };
+    });
   };
 
-  config.result.assertions = lib.optionalAttrs (config.manifest.features.API) (
+  config.result.assertions = (
     lib.mapAttrs' (roleName: _role: {
       name = "${roleName}";
       value = {
+        # TODO: make the path to access the schema shorter
         message = ''
           `roles.${roleName}.interface` is not JSON serializable.
 
-          but 'manifest.features.API' is enabled, which requires all 'roles-interfaces' of this module to be a subset of JSON.
+          'clan.services' modules require all 'roles.*.interfaces' to be subset of JSON.
 
-          clan.service module '${config.manifest.name}
+          : clan.service module '${config.manifest.name}
+
+          To see the evaluation problem run
+
+          nix eval .#clanInternals.inventoryClass.distributedServices.importedModulesEvaluated.${attrName}.config.result.api.schema.${roleName}
         '';
         assertion = (builtins.tryEval (lib.deepSeq config.result.api.schema.${roleName} true)).success;
       };
diff --git a/lib/inventory/distributed-service/inventory-adapter.nix b/lib/inventory/distributed-service/inventory-adapter.nix
index 2e6978952..03447ca65 100644
--- a/lib/inventory/distributed-service/inventory-adapter.nix
+++ b/lib/inventory/distributed-service/inventory-adapter.nix
@@ -118,7 +118,7 @@ let
 
   # TODO: Eagerly check the _class of the resolved module
   importedModulesEvaluated = lib.mapAttrs (
-    _module_ident: instances:
+    module_ident: instances:
     (lib.evalModules {
       class = "clan.service";
       modules =
@@ -128,7 +128,10 @@ let
           (builtins.head instances).instance.resolvedModule
 
           # feature modules
-          (lib.modules.importApply ./api-feature.nix { inherit clanLib; })
+          (lib.modules.importApply ./api-feature.nix {
+            inherit clanLib;
+            attrName = module_ident;
+          })
         ]
         # Include all the instances that correlate to the resolved module
         ++ (builtins.map (v: {