diff --git a/.gitignore b/.gitignore
index 5e778b5c554a04a2d257e3816a54a8941e77dd13..ace00ac8ad581331eced697688888b9bcb69cde3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,6 +13,11 @@ docs/vale/styles/*
 venv/
 .venv/
 
+.mypy_cache
+.pytest_cache
+.ruff_cache
+build/
+
 # Ignore files generated by apidoc
 docs/source/lso.rst
 docs/source/lso.*.rst
diff --git a/README.md b/README.md
index 7f61c0131b2db6771ac43889f408f759f7c76236..5026025e275a6e41d2d107405c6dd55da4dd1084 100644
--- a/README.md
+++ b/README.md
@@ -29,13 +29,10 @@ Fill in environment variables and run the command to generate the Ansible invent
 # Rewritting environment variables
 ## URL of the WFO API (change IP only)
 export api_url=http://127.0.0.1:8080/api/v1/subscriptions/routers
-## Full paths where this tool will save variables and inventory files
-export host_vars_dir=/path/to/base/hostvars/dir
-export hosts_file_dir=/path/to/base/hosts/dir
-## Full path where this tool will save the WFO variables
-export vars_file_name=wfo_vars.yaml
 ## Token provided by each GSO instance admin (varies per environment)
 export gso_api_key=<fill_with_gso_token>
+## Full paths where AIG will save host_vars
+export host_vars_dir=/path/to/base/host_vars/dir
 
 # Execution of the command to generate the Ansible inventory files
 ansible_inventory_generator
@@ -63,6 +60,4 @@ pip install -U pip setuptools wheel
 
 ### 403 error when running the `ansible_inventory_generator` command
 
-This tool cannot reach the WFO API because it is authenticated.
-Correct it by redeploying WFO by first running `export OAUTH2_ACTIVE=false` and then re-running WFO.
-Alternatively, change `export api_url` to an authenticated instance of GSO.
\ No newline at end of file
+This tool cannot reach the GSO API because it is authenticated. Use a correct gso_api_key environment variable.
diff --git a/ansible_inventory_generator/app.py b/ansible_inventory_generator/app.py
index 7b535c2bb502d6fec84aed0f996a3591affffbfb..1591e861b7c8073b40bbeeb64eb80a391e26c561 100644
--- a/ansible_inventory_generator/app.py
+++ b/ansible_inventory_generator/app.py
@@ -56,7 +56,7 @@ def write_hosts_file(groups: dict, hosts_file: Path) -> None:
 def generate_host_vars_and_hosts_file(router_subscriptions: list, temp_dir: Path) -> None:
     """Process router subscriptions data."""
     groups: dict[str, list[str]] = {}
-    host_vars_dir = temp_dir / "hostvars"
+    host_vars_dir = temp_dir / "host_vars"
     host_vars_dir.mkdir()
 
     for router_subscription in router_subscriptions:
@@ -67,7 +67,7 @@ def generate_host_vars_and_hosts_file(router_subscriptions: list, temp_dir: Path
 
         write_host_vars(host_name, router, host_vars_dir)
 
-        vendor_group = router.get("router_vendor", "").lower()
+        vendor_group = router.get("vendor", "").lower()
         role_group = f"{router.get('router_role', '')}_routers"
 
         groups.setdefault(vendor_group, []).append(host_name)
@@ -78,7 +78,7 @@ def generate_host_vars_and_hosts_file(router_subscriptions: list, temp_dir: Path
 
 
 @contextmanager
-def safe_write(temp_dir: Path, old_vars_dir: Path, old_hosts_file: Path) -> Generator[Path, None, None]:
+def safe_write(temp_dir: Path, old_host_vars_dir: Path) -> Generator[Path, None, None]:
     temp_dir.mkdir(exist_ok=True)
 
     try:
@@ -88,11 +88,11 @@ def safe_write(temp_dir: Path, old_vars_dir: Path, old_hosts_file: Path) -> Gene
         typer.echo(f"Error: {e}")
         sys.exit(1)
     else:
-        if old_vars_dir.exists():
-            shutil.rmtree(old_vars_dir)
+        if old_host_vars_dir.exists():
+            shutil.rmtree(old_host_vars_dir)
 
-        shutil.copytree(temp_dir, old_vars_dir)  # Copy new host vars dir
-        shutil.copy(temp_dir / "hosts.yaml", old_hosts_file)  # Copy new hosts file
+        shutil.copytree(temp_dir, old_host_vars_dir)  # Copy new host_vars dir
+        shutil.copy(temp_dir / "hosts.yaml", old_host_vars_dir)  # Copy new hosts.yaml file
         shutil.rmtree(temp_dir)
 
 
@@ -112,9 +112,8 @@ def generate_inventory_from_api() -> None:
 
     temp_dir = Path(tempfile.mkdtemp())
     old_host_vars_dir = Path(settings.host_vars_dir)
-    old_hosts_file = Path(settings.hosts_file_dir)
 
-    with safe_write(temp_dir, old_host_vars_dir, old_hosts_file) as temp_dir:
+    with safe_write(temp_dir, old_host_vars_dir) as temp_dir:
         generate_host_vars_and_hosts_file(router_subscriptions, temp_dir)
 
 
diff --git a/ansible_inventory_generator/config.py b/ansible_inventory_generator/config.py
index 35e125bbb4ee077de6b67c84969c847accd404d8..8029c7a20563b3a03f56452cdd037dc75c3021aa 100644
--- a/ansible_inventory_generator/config.py
+++ b/ansible_inventory_generator/config.py
@@ -3,10 +3,9 @@ from pydantic.v1 import BaseSettings
 
 class Settings(BaseSettings):
     api_url: str
-    host_vars_dir: str
-    vars_file_name: str
-    hosts_file_dir: str
     gso_api_key: str
+    host_vars_dir: str
+    vars_file_name: str = "gso.yaml"
 
     class Config:
         env_file = "../.env"
diff --git a/tests/test_inventory_generator.py b/tests/test_inventory_generator.py
index 2b5fc13d7cf81cebbb60480724bff4b7af42e950..abe34f603c76cb200a4cb08032b047de808b8a40 100644
--- a/tests/test_inventory_generator.py
+++ b/tests/test_inventory_generator.py
@@ -55,7 +55,7 @@ def mocked_subscription_api_data():
                 "router_si_ipv4_network": "62.40.97.222/31",
                 "router_ias_lt_ipv4_network": "83.97.89.116/31",
                 "router_ias_lt_ipv6_network": "2001:798:1::2a4/126",
-                "router_vendor": "nokia",
+                "vendor": "nokia",
                 "router_role": "p",
                 "router_site": {
                     "name": "SiteBlock",
@@ -118,7 +118,7 @@ def mocked_subscription_api_data():
                 "router_si_ipv4_network": "62.40.97.222/31",
                 "router_ias_lt_ipv4_network": "83.97.89.116/31",
                 "router_ias_lt_ipv6_network": "2001:798:1::2a4/126",
-                "router_vendor": "juniper",
+                "vendor": "juniper",
                 "router_role": "amt",
                 "router_site": {
                     "name": "SiteBlock",
@@ -149,14 +149,14 @@ def mocked_subscription_api_data():
 
 @pytest.fixture()
 def setup_test(tmp_dir, mocked_subscription_api_data):
-    with patch("ansible_inventory_generator.app.load_settings") as mock_load_settings, patch(
-        "requests.get"
-    ) as mock_get:
+    with (
+        patch("ansible_inventory_generator.app.load_settings") as mock_load_settings,
+        patch("requests.get") as mock_get,
+    ):
         mock_load_settings.return_value = Settings(
             api_url="http://test",
             host_vars_dir=str(tmp_dir),
             vars_file_name="wfo_vars.yaml",
-            hosts_file_dir=str(tmp_dir),
             gso_api_key="random_gso_api_key",
         )
 
@@ -170,8 +170,8 @@ def setup_test(tmp_dir, mocked_subscription_api_data):
 
 def test_generate_inventory_from_api_valid_json(setup_test, tmp_dir, mocked_subscription_api_data):
     hosts_file = tmp_dir / "hosts.yaml"
-    amsterdam_host_vars = tmp_dir / "hostvars/amsterdam.nl.geant.net/wfo_vars.yaml"
-    utrecht_host_vars = tmp_dir / "hostvars/utrecht.nl.geant.net/wfo_vars.yaml"
+    amsterdam_host_vars = tmp_dir / "host_vars/amsterdam.nl.geant.net/wfo_vars.yaml"
+    utrecht_host_vars = tmp_dir / "host_vars/utrecht.nl.geant.net/wfo_vars.yaml"
 
     assert not amsterdam_host_vars.exists()
     assert not utrecht_host_vars.exists()
@@ -218,8 +218,8 @@ def test_inventory_generation_handles_exceptions_and_preserves_file_integrity(
 ):
     paths = {
         "hosts": tmp_dir / "hosts.yaml",
-        "ams_vars": tmp_dir / "hostvars/amsterdam.nl.geant.net/wfo_vars.yaml",
-        "utr_vars": tmp_dir / "hostvars/utrecht.nl.geant.net/wfo_vars.yaml",
+        "ams_vars": tmp_dir / "host_vars/amsterdam.nl.geant.net/wfo_vars.yaml",
+        "utr_vars": tmp_dir / "host_vars/utrecht.nl.geant.net/wfo_vars.yaml",
     }
 
     file_contents = {