diff --git a/src/crewai/types/crew_chat.py b/src/crewai/types/crew_chat.py
index 354642442..2873700f4 100644
--- a/src/crewai/types/crew_chat.py
+++ b/src/crewai/types/crew_chat.py
@@ -1,16 +1,22 @@
-from typing import List
+"""Crew chat input models.
+
+This module provides models for defining chat inputs and fields
+for crew interactions.
+"""
 
 from pydantic import BaseModel, Field
 
 
 class ChatInputField(BaseModel):
-    """
-    Represents a single required input for the crew, with a name and short description.
+    """Represents a single required input for the crew.
+
     Example:
-        {
-            "name": "topic",
-            "description": "The topic to focus on for the conversation"
-        }
+        ```python
+        field = ChatInputField(
+            name="topic",
+            description="The topic to focus on for the conversation"
+        )
+        ```
     """
 
     name: str = Field(..., description="The name of the input field")
@@ -18,23 +24,25 @@ class ChatInputField(BaseModel):
 
 
 class ChatInputs(BaseModel):
-    """
-    Holds a high-level crew_description plus a list of ChatInputFields.
+    """Holds crew metadata and input field definitions.
+
     Example:
-        {
-            "crew_name": "topic-based-qa",
-            "crew_description": "Use this crew for topic-based Q&A",
-            "inputs": [
-                {"name": "topic", "description": "The topic to focus on"},
-                {"name": "username", "description": "Name of the user"},
+        ```python
+        inputs = ChatInputs(
+            crew_name="topic-based-qa",
+            crew_description="Use this crew for topic-based Q&A",
+            inputs=[
+                ChatInputField(name="topic", description="The topic to focus on"),
+                ChatInputField(name="username", description="Name of the user"),
             ]
-        }
+        )
+        ```
     """
 
     crew_name: str = Field(..., description="The name of the crew")
     crew_description: str = Field(
         ..., description="A description of the crew's purpose"
     )
-    inputs: List[ChatInputField] = Field(
+    inputs: list[ChatInputField] = Field(
         default_factory=list, description="A list of input fields for the crew"
     )
diff --git a/src/crewai/types/hitl.py b/src/crewai/types/hitl.py
index 80105a29f..d5fd33e14 100644
--- a/src/crewai/types/hitl.py
+++ b/src/crewai/types/hitl.py
@@ -1,18 +1,37 @@
-from typing import List, Dict, TypedDict
+"""Human-in-the-loop (HITL) type definitions.
+
+This module provides type definitions for human-in-the-loop interactions
+in crew executions.
+"""
+
+from typing import TypedDict
 
 
 class HITLResumeInfo(TypedDict, total=False):
-    """HITL resume information passed from flow to crew."""
+    """HITL resume information passed from flow to crew.
+
+    Attributes:
+        task_id: Unique identifier for the task.
+        crew_execution_id: Unique identifier for the crew execution.
+        task_key: Key identifying the specific task.
+        task_output: Output from the task before human intervention.
+        human_feedback: Feedback provided by the human.
+        previous_messages: History of messages in the conversation.
+    """
 
     task_id: str
     crew_execution_id: str
     task_key: str
     task_output: str
     human_feedback: str
-    previous_messages: List[Dict[str, str]]
+    previous_messages: list[dict[str, str]]
 
 
 class CrewInputsWithHITL(TypedDict, total=False):
-    """Crew inputs that may contain HITL resume information."""
+    """Crew inputs that may contain HITL resume information.
+
+    Attributes:
+        _hitl_resume: Optional HITL resume information for continuing execution.
+    """
 
     _hitl_resume: HITLResumeInfo
diff --git a/src/crewai/types/usage_metrics.py b/src/crewai/types/usage_metrics.py
index e87a79e33..77e9ef598 100644
--- a/src/crewai/types/usage_metrics.py
+++ b/src/crewai/types/usage_metrics.py
@@ -1,9 +1,15 @@
+"""Usage metrics tracking for CrewAI execution.
+
+This module provides models for tracking token usage and request metrics
+during crew and agent execution.
+"""
+
 from pydantic import BaseModel, Field
+from typing_extensions import Self
 
 
 class UsageMetrics(BaseModel):
-    """
-    Model to track usage metrics for the crew's execution.
+    """Track usage metrics for crew execution.
 
     Attributes:
         total_tokens: Total number of tokens used.
@@ -27,12 +33,11 @@ class UsageMetrics(BaseModel):
         default=0, description="Number of successful requests made."
     )
 
-    def add_usage_metrics(self, usage_metrics: "UsageMetrics"):
-        """
-        Add the usage metrics from another UsageMetrics object.
+    def add_usage_metrics(self, usage_metrics: Self) -> None:
+        """Add usage metrics from another UsageMetrics object.
 
         Args:
-            usage_metrics (UsageMetrics): The usage metrics to add.
+            usage_metrics: The usage metrics to add.
         """
         self.total_tokens += usage_metrics.total_tokens
         self.prompt_tokens += usage_metrics.prompt_tokens