diff --git a/src/smolagents/agents.py b/src/smolagents/agents.py
index 7e80161..eddced1 100644
--- a/src/smolagents/agents.py
+++ b/src/smolagents/agents.py
@@ -225,6 +225,10 @@ class MultiStepAgent:
             messages.extend(memory_step.to_messages(summary_mode=summary_mode))
         return messages
 
+    def visualize(self):
+        """Creates a rich tree visualization of the agent's structure."""
+        self.logger.visualize_agent_tree(self)
+
     def extract_action(self, model_output: str, split_token: str) -> Tuple[str, str]:
         """
         Parse action from the LLM output
diff --git a/src/smolagents/models.py b/src/smolagents/models.py
index 2dab05a..d2fdd47 100644
--- a/src/smolagents/models.py
+++ b/src/smolagents/models.py
@@ -241,8 +241,6 @@ class Model:
     def __init__(self, **kwargs):
         self.last_input_token_count = None
         self.last_output_token_count = None
-        # Set default values for common parameters
-        kwargs.setdefault("max_tokens", 4096)
         self.kwargs = kwargs
 
     def _prepare_completion_kwargs(
@@ -643,15 +641,19 @@ class LiteLLMModel(Model):
             The base URL of the OpenAI-compatible API server.
         api_key (`str`, *optional*):
             The API key to use for authentication.
+        custom_role_conversions (`dict[str, str]`, *optional*):
+            Custom role conversion mapping to convert message roles in others.
+            Useful for specific models that do not support specific message roles like "system".
         **kwargs:
             Additional keyword arguments to pass to the OpenAI API.
     """
 
     def __init__(
         self,
-        model_id="anthropic/claude-3-5-sonnet-20240620",
+        model_id: str = "anthropic/claude-3-5-sonnet-20240620",
         api_base=None,
         api_key=None,
+        custom_role_conversions: Optional[Dict[str, str]] = None,
         **kwargs,
     ):
         try:
@@ -667,6 +669,7 @@ class LiteLLMModel(Model):
         litellm.add_function_to_prompt = True
         self.api_base = api_base
         self.api_key = api_key
+        self.custom_role_conversions = custom_role_conversions
 
     def __call__(
         self,
@@ -687,6 +690,7 @@ class LiteLLMModel(Model):
             api_base=self.api_base,
             api_key=self.api_key,
             convert_images_to_image_urls=True,
+            custom_role_conversions=self.custom_role_conversions,
             **kwargs,
         )
 
diff --git a/src/smolagents/monitoring.py b/src/smolagents/monitoring.py
index 53c433f..33ae2ab 100644
--- a/src/smolagents/monitoring.py
+++ b/src/smolagents/monitoring.py
@@ -23,7 +23,9 @@ from rich.console import Console, Group
 from rich.panel import Panel
 from rich.rule import Rule
 from rich.syntax import Syntax
+from rich.table import Table
 from rich.text import Text
+from rich.tree import Tree
 
 
 class Monitor:
@@ -162,5 +164,42 @@ class AgentLogger:
             )
         )
 
+    def visualize_agent_tree(self, agent):
+        def create_tools_section(tools_dict):
+            table = Table(show_header=True, header_style="bold")
+            table.add_column("Name", style="blue")
+            table.add_column("Description")
+            table.add_column("Arguments")
+
+            for name, tool in tools_dict.items():
+                args = [
+                    f"{arg_name} (`{info.get('type', 'Any')}`{', optional' if info.get('optional') else ''}): {info.get('description', '')}"
+                    for arg_name, info in getattr(tool, "inputs", {}).items()
+                ]
+                table.add_row(name, getattr(tool, "description", str(tool)), "\n".join(args))
+
+            return Group(Text("🛠️ Tools", style="bold italic blue"), table)
+
+        def build_agent_tree(parent_tree, agent_obj):
+            """Recursively builds the agent tree."""
+            if agent_obj.tools:
+                parent_tree.add(create_tools_section(agent_obj.tools))
+
+            if agent_obj.managed_agents:
+                agents_branch = parent_tree.add("[bold italic blue]🤖 Managed agents")
+                for name, managed_agent in agent_obj.managed_agents.items():
+                    agent_node_text = f"[bold {YELLOW_HEX}]{name} - {managed_agent.agent.__class__.__name__}"
+                    agent_tree = agents_branch.add(agent_node_text)
+                    if hasattr(managed_agent, "description"):
+                        agent_tree.add(
+                            f"[bold italic blue]📝 Description:[/bold italic blue] {managed_agent.description}"
+                        )
+                    if hasattr(managed_agent, "agent"):
+                        build_agent_tree(agent_tree, managed_agent.agent)
+
+        main_tree = Tree(f"[bold {YELLOW_HEX}]{agent.__class__.__name__}")
+        build_agent_tree(main_tree, agent)
+        self.console.print(main_tree)
+
 
 __all__ = ["AgentLogger", "Monitor"]