docs: update agent_execution_loop example code

Signed-off-by: reidliu <[email protected]>

docs/source/building_applications/agent_execution_loop.md

@@ -67,10 +67,17 @@ sequenceDiagram
 Each step in this process can be monitored and controlled through configurations. Here's an example that demonstrates monitoring the agent's execution:
 
 ```python
+from llama_stack_client import LlamaStackClient
+from llama_stack_client.lib.agents.agent import Agent
 from llama_stack_client.lib.agents.event_logger import EventLogger
+from llama_stack_client.types.agent_create_params import AgentConfig
 from rich.pretty import pprint
 
+# Replace host and port
+client = LlamaStackClient(base_url=f"http://{HOST}:{PORT}")
+
 agent_config = AgentConfig(
+    # Check with `llama-stack-client models list`
     model="Llama3.2-3B-Instruct",
     instructions="You are a helpful assistant",
     # Enable both RAG and tool usage
@@ -81,7 +88,7 @@ agent_config = AgentConfig(
         },
         "builtin::code_interpreter",
     ],
-    # Configure safety
+    # Configure safety (optional)
     input_shields=["llama_guard"],
     output_shields=["llama_guard"],
     # Control the inference loop