diff --git a/swh/indexer/indexer.py b/swh/indexer/indexer.py
--- a/swh/indexer/indexer.py
+++ b/swh/indexer/indexer.py
@@ -169,12 +169,12 @@
         self.log = logging.getLogger('swh.indexer')
         self.tools = list(self.register_tools(self.config['tools']))
 
-    def check(self):
+    def check(self, *, check_tools=True):
         """Check the indexer's configuration is ok before proceeding.
            If ok, does nothing. If not raise error.
 
         """
-        if not self.tools:
+        if check_tools and not self.tools:
             raise ValueError('Tools %s is unknown, cannot continue' %
                              self.tools)
 
@@ -211,7 +211,8 @@
         else:
             raise ValueError('Configuration tool(s) must be a dict or list!')
 
-        return self.idx_storage.indexer_configuration_add(tools)
+        if tools:
+            return self.idx_storage.indexer_configuration_add(tools)
 
     @abc.abstractmethod
     def index(self, id, data):
diff --git a/swh/indexer/metadata.py b/swh/indexer/metadata.py
--- a/swh/indexer/metadata.py
+++ b/swh/indexer/metadata.py
@@ -163,13 +163,13 @@
                 - translated_metadata: dict of retrieved metadata
 
         """
-        try:
-            result = {
-                'id': rev['id'].decode(),
-                'indexer_configuration_id': self.tool['id'],
-                'translated_metadata': None
-            }
+        result = {
+            'id': rev['id'].decode(),
+            'indexer_configuration_id': self.tool['id'],
+            'translated_metadata': None
+        }
 
+        try:
             root_dir = rev['directory']
             dir_ls = self.storage.directory_ls(root_dir, recursive=False)
             files = [entry for entry in dir_ls if entry['type'] == 'file']
@@ -268,6 +268,14 @@
 
 
 class OriginMetadataIndexer(OriginIndexer):
+    ADDITIONAL_CONFIG = {
+        'tools': ('list', [])
+    }
+
+    def check(self, **kwargs):
+        kwargs['check_tools'] = False
+        super().check(**kwargs)
+
     def filter(self, ids):
         return ids
 
diff --git a/swh/indexer/storage/__init__.py b/swh/indexer/storage/__init__.py
--- a/swh/indexer/storage/__init__.py
+++ b/swh/indexer/storage/__init__.py
@@ -603,6 +603,7 @@
 
                 - **id**: sha1_git of revision
                 - **translated_metadata**: arbitrary dict
+                - **indexer_configuration_id**: tool used to compute metadata
 
             conflict_update: Flag to determine if we want to overwrite (true)
               or skip duplicates (false, the default)
@@ -649,6 +650,7 @@
                 - **from_revision**: sha1 id of the revision used to generate
                   these metadata.
                 - **metadata**: arbitrary dict
+                - **indexer_configuration_id**: tool used to compute metadata
 
             conflict_update: Flag to determine if we want to overwrite (true)
               or skip duplicates (false, the default)
diff --git a/swh/indexer/tests/test_origin_metadata.py b/swh/indexer/tests/test_origin_metadata.py
--- a/swh/indexer/tests/test_origin_metadata.py
+++ b/swh/indexer/tests/test_origin_metadata.py
@@ -26,18 +26,13 @@
                     'url': 'http://localhost:9999',
                 }
             },
-            'tools': {
-                'name': 'origin-metadata',
-                'version': '0.0.1',
-                'configuration': {}
-            }
+            'tools': [],
         }
         self.storage = MockStorage()
         self.idx_storage = MockIndexerStorage()
         self.log = logging.getLogger('swh.indexer')
         self.objstorage = MockObjStorage()
         self.tools = self.register_tools(self.config['tools'])
-        self.tool = self.tools[0]
         self.results = []
 
 
diff --git a/swh/indexer/tests/test_utils.py b/swh/indexer/tests/test_utils.py
--- a/swh/indexer/tests/test_utils.py
+++ b/swh/indexer/tests/test_utils.py
@@ -271,9 +271,14 @@
     added_data = []
 
     def indexer_configuration_add(self, tools):
-        tool = tools[0]
+        results = []
+        for tool in tools:
+            results.append(self._indexer_configuration_add_one(tool))
+        return results
+
+    def _indexer_configuration_add_one(self, tool):
         if tool['tool_name'] == 'swh-metadata-translator':
-            return [{
+            return {
                 'id': 30,
                 'tool_name': 'swh-metadata-translator',
                 'tool_version': '0.0.1',
@@ -281,9 +286,9 @@
                     'type': 'local',
                     'context': 'NpmMapping'
                 },
-            }]
+            }
         elif tool['tool_name'] == 'swh-metadata-detector':
-            return [{
+            return {
                 'id': 7,
                 'tool_name': 'swh-metadata-detector',
                 'tool_version': '0.0.1',
@@ -291,14 +296,14 @@
                     'type': 'local',
                     'context': 'NpmMapping'
                 },
-            }]
+            }
         elif tool['tool_name'] == 'origin-metadata':
-            return [{
+            return {
                 'id': 8,
                 'tool_name': 'origin-metadata',
                 'tool_version': '0.0.1',
                 'tool_configuration': {},
-            }]
+            }
         else:
             assert False, 'Unknown tool {tool_name}'.format(**tool)