diff --git a/checks/flake-module.nix b/checks/flake-module.nix
index 5e47cdccd..fec530b8b 100644
--- a/checks/flake-module.nix
+++ b/checks/flake-module.nix
@@ -21,6 +21,7 @@ in
       pkgs,
       lib,
       self',
+      system,
       ...
     }:
     {
@@ -83,7 +84,7 @@ in
                   schema =
                     (self.clanLib.inventory.evalClanService {
                       modules = [ m ];
-                      key = "checks";
+                      prefix = [ "checks" system ];
                     }).config.result.api.schema;
                 in
                 schema
diff --git a/clanServices/hello-world/default.nix b/clanServices/hello-world/default.nix
index 7a835bede..86bfbdb1e 100644
--- a/clanServices/hello-world/default.nix
+++ b/clanServices/hello-world/default.nix
@@ -4,7 +4,15 @@
   _class = "clan.service";
   manifest.name = "clan-core/hello-word";
 
-  roles.peer = { };
+  roles.peer = {
+    interface =
+      { lib, ... }:
+      {
+        options.foo = lib.mkOption {
+          type = lib.types.str;
+        };
+      };
+  };
 
   perMachine =
     { machine, ... }:
diff --git a/clanServices/hello-world/flake-module.nix b/clanServices/hello-world/flake-module.nix
index 9a1c14a27..0c85e0630 100644
--- a/clanServices/hello-world/flake-module.nix
+++ b/clanServices/hello-world/flake-module.nix
@@ -50,6 +50,7 @@ in
           hello-service = import ./tests/vm/default.nix {
             inherit module;
             inherit self inputs pkgs;
+            # clanLib is exposed from inputs.clan-core
             clanLib = self.clanLib;
           };
         };
diff --git a/lib/build-clan/interface.nix b/lib/build-clan/interface.nix
index db090ec2b..fc61197e7 100644
--- a/lib/build-clan/interface.nix
+++ b/lib/build-clan/interface.nix
@@ -10,6 +10,11 @@ let
 in
 {
   options = {
+    _prefix = lib.mkOption {
+      type = types.listOf types.str;
+      internal = true;
+      default = [ ];
+    };
     self = lib.mkOption {
       type = types.raw;
       default = self;
diff --git a/lib/build-clan/module.nix b/lib/build-clan/module.nix
index acb7a2519..169c058e0 100644
--- a/lib/build-clan/module.nix
+++ b/lib/build-clan/module.nix
@@ -44,6 +44,7 @@ let
     buildInventory {
       inherit inventory directory;
       flakeInputs = config.self.inputs;
+      prefix = config._prefix ++ [ "inventoryClass" ];
     }
   );
 
diff --git a/lib/inventory/build-inventory/default.nix b/lib/inventory/build-inventory/default.nix
index 1a4997873..0236eb2c5 100644
--- a/lib/inventory/build-inventory/default.nix
+++ b/lib/inventory/build-inventory/default.nix
@@ -12,8 +12,10 @@ let
       inventory,
       directory,
       flakeInputs,
+      prefix ? [ ],
     }:
     (lib.evalModules {
+      # TODO: remove clanLib from specialArgs
       specialArgs = {
         inherit clanLib;
       };
@@ -24,13 +26,16 @@ let
           # config.distributedServices.allMachines.${name} or [ ];
           { config, ... }:
           {
+
             distributedServices = clanLib.inventory.mapInstances {
               inherit (config) inventory;
               inherit flakeInputs;
+              prefix = prefix ++ [ "distributedServices" ];
             };
             machines = lib.mapAttrs (_machineName: v: {
               machineImports = v;
             }) config.distributedServices.allMachines;
+
           }
         )
       ];
diff --git a/lib/inventory/distributed-service/api-feature.nix b/lib/inventory/distributed-service/api-feature.nix
index 1266bb68a..f745251f0 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, attrName }:
+{ clanLib, prefix }:
 let
   converter = clanLib.jsonschema {
     includeDefaults = true;
@@ -45,7 +45,7 @@ in
 
           To see the evaluation problem run
 
-          nix eval .#clanInternals.inventoryClass.distributedServices.importedModulesEvaluated.${attrName}.config.result.api.schema.${roleName}
+          nix eval .#${lib.concatStringsSep "." prefix}.config.result.api.schema.${roleName}
         '';
         assertion = (builtins.tryEval (lib.deepSeq config.result.api.schema.${roleName} true)).success;
       };
diff --git a/lib/inventory/distributed-service/inventory-adapter.nix b/lib/inventory/distributed-service/inventory-adapter.nix
index e899564c8..bbedc467f 100644
--- a/lib/inventory/distributed-service/inventory-adapter.nix
+++ b/lib/inventory/distributed-service/inventory-adapter.nix
@@ -16,15 +16,14 @@
 }:
 let
   evalClanService =
-    { modules, key }:
+    { modules, prefix }:
     (lib.evalModules {
       class = "clan.service";
       modules = [
         ./service-module.nix
         # feature modules
         (lib.modules.importApply ./api-feature.nix {
-          inherit clanLib;
-          attrName = key;
+          inherit clanLib prefix;
         })
       ] ++ modules;
     });
@@ -37,6 +36,7 @@ in
       flakeInputs,
       # The clan inventory
       inventory,
+      prefix ? [ ],
     }:
     let
       # machineHasTag = machineName: tagName: lib.elem tagName inventory.machines.${machineName}.tags;
@@ -138,7 +138,7 @@ in
       importedModulesEvaluated = lib.mapAttrs (
         module_ident: instances:
         evalClanService {
-          key = module_ident;
+          prefix = prefix ++ [ module_ident ];
           modules =
             [
               # Import the resolved module.
diff --git a/lib/test/default.nix b/lib/test/default.nix
index 05d4e5ffe..3849f2006 100644
--- a/lib/test/default.nix
+++ b/lib/test/default.nix
@@ -22,6 +22,9 @@ in
       pkgs,
       self,
       useContainers ? true,
+      # Displayed for better error messages, otherwise the placeholder
+      system ? "<system>",
+      attrName ? "<check_name>",
       ...
     }:
     let
@@ -60,6 +63,15 @@ in
               };
               modules = [
                 clanLib.buildClanModule.flakePartsModule
+                {
+                  _prefix = [
+                    "checks"
+                    system
+                    attrName
+                    "config"
+                    "clan"
+                  ];
+                }
               ];
             };
           };