diff --git a/chatmastermind/ai_factory.py b/chatmastermind/ai_factory.py
index 420b287..a3cf9c3 100644
--- a/chatmastermind/ai_factory.py
+++ b/chatmastermind/ai_factory.py
@@ -17,7 +17,7 @@ def create_ai(args: argparse.Namespace, config: Config) -> AI:  # noqa: 11
     is not found, it uses the first AI in the list.
     """
     ai_conf: AIConfig
-    if args.AI:
+    if 'AI' in args and args.AI:
         try:
             ai_conf = config.ais[args.AI]
         except KeyError:
@@ -32,11 +32,11 @@ def create_ai(args: argparse.Namespace, config: Config) -> AI:  # noqa: 11
 
     if ai_conf.name == 'openai':
         ai = OpenAI(cast(OpenAIConfig, ai_conf))
-        if args.model:
+        if 'model' in args and args.model:
             ai.config.model = args.model
-        if args.max_tokens:
+        if 'max_tokens' in args and args.max_tokens:
             ai.config.max_tokens = args.max_tokens
-        if args.temperature:
+        if 'temperature' in args and args.temperature:
             ai.config.temperature = args.temperature
         return ai
     else:
diff --git a/chatmastermind/ais/openai.py b/chatmastermind/ais/openai.py
index a388a7a..0e7ad41 100644
--- a/chatmastermind/ais/openai.py
+++ b/chatmastermind/ais/openai.py
@@ -62,7 +62,12 @@ class OpenAI(AI):
         """
         Return all models supported by this AI.
         """
-        raise NotImplementedError
+        ret = []
+        for engine in sorted(openai.Engine.list()['data'], key=lambda x: x['id']):
+            if engine['ready']:
+                ret.append(engine['id'])
+        ret.sort()
+        return ret
 
     def print_models(self) -> None:
         """
diff --git a/chatmastermind/main.py b/chatmastermind/main.py
index 99aca09..7e18185 100755
--- a/chatmastermind/main.py
+++ b/chatmastermind/main.py
@@ -100,6 +100,7 @@ def create_parser() -> argparse.ArgumentParser:
                                              help="Manage configuration",
                                              aliases=['c'])
     config_cmd_parser.set_defaults(func=config_cmd)
+    config_cmd_parser.add_argument('-A', '--AI', help='AI ID to use')
     config_group = config_cmd_parser.add_mutually_exclusive_group(required=True)
     config_group.add_argument('-l', '--list-models', help="List all available models",
                               action='store_true')