diff --git a/dapr_agents/types/llm.py b/dapr_agents/types/llm.py
index 65c03369..0d5b442c 100644
--- a/dapr_agents/types/llm.py
+++ b/dapr_agents/types/llm.py
@@ -1,4 +1,4 @@
-from typing import List, Union, Optional, Dict, Any, Literal, IO, Tuple
+from typing import List, Union, Optional, Dict, Any, Literal, IO, Tuple, cast
 from pydantic import BaseModel, Field, model_validator, field_validator, ConfigDict
 from pydantic_core import PydanticUseDefault
 from pathlib import Path
@@ -113,7 +113,7 @@ class OpenAIModelConfig(OpenAIClientConfig):
     type: Literal["openai"] = Field(
         "openai", description="Type of the model, must always be 'openai'"
     )
-    name: str = Field(default=None, description="Name of the OpenAI model")
+    name: str = Field(default="", description="Name of the OpenAI model")
 
 
 class AzureOpenAIModelConfig(AzureOpenAIClientConfig):
@@ -127,7 +127,7 @@ class HFHubModelConfig(HFInferenceClientConfig):
         "huggingface", description="Type of the model, must always be 'huggingface'"
     )
     name: str = Field(
-        default=None, description="Name of the model available through Hugging Face"
+        default="", description="Name of the model available through Hugging Face"
     )
 
 
@@ -136,7 +136,7 @@ class NVIDIAModelConfig(NVIDIAClientConfig):
         "nvidia", description="Type of the model, must always be 'nvidia'"
     )
     name: str = Field(
-        default=None, description="Name of the model available through NVIDIA"
+        default="", description="Name of the model available through NVIDIA"
     )
 
 
@@ -340,6 +340,14 @@ def sync_model_name(cls, values: dict):
             elif configuration.get("type") == "nvidia":
                 configuration = NVIDIAModelConfig(**configuration)
 
+        configuration = cast(
+            OpenAIModelConfig
+            | AzureOpenAIModelConfig
+            | HFHubModelConfig
+            | NVIDIAModelConfig,
+            configuration,
+        )
+
         # Ensure 'parameters' is properly validated as a model, not a dict
         if isinstance(parameters, dict):
             if configuration and isinstance(configuration, OpenAIModelConfig):
@@ -351,12 +359,27 @@ def sync_model_name(cls, values: dict):
             elif configuration and isinstance(configuration, NVIDIAModelConfig):
                 parameters = NVIDIAChatCompletionParams(**parameters)
 
+        parameters = cast(
+            OpenAIChatCompletionParams
+            | HFHubChatCompletionParams
+            | NVIDIAChatCompletionParams,
+            parameters,
+        )
+
         if configuration and parameters:
             # Check if 'name' or 'azure_deployment' is explicitly set
             if "name" in configuration.model_fields_set:
-                parameters.model = configuration.name
+                parameters.model = (
+                    configuration.name
+                    if not isinstance(configuration, AzureOpenAIModelConfig)
+                    else None
+                )
             elif "azure_deployment" in configuration.model_fields_set:
-                parameters.model = configuration.azure_deployment
+                parameters.model = (
+                    configuration.azure_deployment
+                    if isinstance(configuration, AzureOpenAIModelConfig)
+                    else None
+                )
 
         values["configuration"] = configuration
         values["parameters"] = parameters
@@ -471,7 +494,7 @@ def validate_file(
         elif isinstance(value, BufferedReader) or (
             hasattr(value, "read") and callable(value.read)
         ):
-            if value.closed:
+            if hasattr(value, "closed") and value.closed:
                 raise ValueError("File-like object must remain open during request.")
             return value
         elif isinstance(value, tuple):
@@ -535,7 +558,7 @@ def validate_file(
         elif isinstance(value, BufferedReader) or (
             hasattr(value, "read") and callable(value.read)
         ):
-            if value.closed:  # Reopen if closed
+            if hasattr(value, "closed") and value.closed:  # Reopen if closed
                 raise ValueError("File-like object must remain open during request.")
             return value
         elif isinstance(value, tuple):
diff --git a/dapr_agents/types/message.py b/dapr_agents/types/message.py
index eac34892..8b6c9c81 100644
--- a/dapr_agents/types/message.py
+++ b/dapr_agents/types/message.py
@@ -1,3 +1,4 @@
+from typing import Any
 from pydantic import (
     BaseModel,
     field_validator,
@@ -5,7 +6,7 @@
     model_validator,
     ConfigDict,
 )
-from typing import List, Optional, Dict, Any
+from typing import List, Optional, Dict
 import json
 
 
@@ -239,6 +240,7 @@ def get_tool_calls(self) -> Optional[List[ToolCall]]:
             return self.tool_calls
         if isinstance(self.tool_calls, ToolCall):
             return [self.tool_calls]
+        return None
 
     def has_tool_calls(self) -> bool:
         """
@@ -250,6 +252,7 @@ def has_tool_calls(self) -> bool:
             return True
         if isinstance(self.tool_calls, ToolCall):
             return True
+        return False
 
 
 class ToolMessage(BaseMessage):
diff --git a/mypy.ini b/mypy.ini
index d16537b4..9fe5198f 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -52,9 +52,6 @@ ignore_errors = True
 [mypy-dapr_agents.tool.base.*]
 ignore_errors = True
 
-[mypy-dapr_agents.types.*]
-ignore_errors = True
-
 [mypy-dapr_agents.workflow.*]
 ignore_errors = True
 
diff --git a/tox.ini b/tox.ini
index 6c2c0a4a..a2d294e6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,11 +1,10 @@
 [tox]
 skipsdist = False
-minversion = 3.9.0
 envlist =
-    py{39,310,311,312,313}
+    py{310,311,312,313}
     flake8,
     ruff,
-    mypy,
+    type,
     pytest
 
 [testenv]