diff --git a/doc/GRAMMAR.md b/doc/GRAMMAR.md
index 86c1ac6..5a9a49a 100644
--- a/doc/GRAMMAR.md
+++ b/doc/GRAMMAR.md
@@ -89,7 +89,7 @@ Tasks can optionally specify which Model to use on the configured inference endp
         This is a user prompt.
 ```
 
-Note that model identifiers may differ between OpenAI compatible endpoint providers, make sure you change your model identifier accordingly when switching providers. If not specified, a default LLM model (`gpt-4o`) is used.
+Note that model identifiers may differ between OpenAI compatible endpoint providers, make sure you change your model identifier accordingly when switching providers. If not specified, a default LLM model (such as `gpt-4.1`) is used.
 
 Parameters to the model can also be specified in the task using the `model_settings` section:
 
diff --git a/examples/model_configs/model_config.yaml b/examples/model_configs/model_config.yaml
index 7197188..b3f1ba1 100644
--- a/examples/model_configs/model_config.yaml
+++ b/examples/model_configs/model_config.yaml
@@ -5,7 +5,5 @@ seclab-taskflow-agent:
   version: "1.0"
   filetype: model_config
 models:
-  sonnet_default: claude-sonnet-4
-  sonnet_latest: claude-sonnet-4.5
   gpt_default: gpt-4.1
-  gpt_latest: gpt-5
+
diff --git a/src/seclab_taskflow_agent/agent.py b/src/seclab_taskflow_agent/agent.py
index dd10487..a7966f2 100644
--- a/src/seclab_taskflow_agent/agent.py
+++ b/src/seclab_taskflow_agent/agent.py
@@ -41,11 +41,11 @@
 api_endpoint = get_AI_endpoint()
 match urlparse(api_endpoint).netloc:
     case AI_API_ENDPOINT_ENUM.AI_API_GITHUBCOPILOT:
-        default_model = "gpt-4o"
+        default_model = "gpt-4.1"
     case AI_API_ENDPOINT_ENUM.AI_API_MODELS_GITHUB:
-        default_model = "openai/gpt-4o"
+        default_model = "openai/gpt-4.1"
     case AI_API_ENDPOINT_ENUM.AI_API_OPENAI:
-        default_model = "gpt-4o"
+        default_model = "gpt-4.1"
     case _:
         default_model = "please-set-default-model-via-env"