diff --git a/src/crewai/agent.py b/src/crewai/agent.py
index 999d1d800..6617f258b 100644
--- a/src/crewai/agent.py
+++ b/src/crewai/agent.py
@@ -137,6 +137,18 @@ class Agent(BaseAgent):
 
     @model_validator(mode="after")
     def post_init_setup(self):
+        # Handle case-insensitive LLM parameter
+        if hasattr(self, 'LLM'):
+            import warnings
+            warnings.warn(
+                "Using 'LLM' parameter is deprecated. Use lowercase 'llm' instead.",
+                DeprecationWarning,
+                stacklevel=2
+            )
+            # Transfer LLM value to llm
+            self.llm = getattr(self, 'LLM')
+            delattr(self, 'LLM')
+
         self._set_knowledge()
         self.agent_ops_agent_name = self.role
         unaccepted_attributes = [
@@ -144,6 +156,10 @@ class Agent(BaseAgent):
             "AWS_SECRET_ACCESS_KEY",
             "AWS_REGION_NAME",
         ]
+        
+        # Initialize LLM parameters with proper typing
+        from typing import Any, Dict, List, Union, Optional
+        llm_params: Dict[str, Any] = {}
 
         # Handle different cases for self.llm
         if isinstance(self.llm, str):
@@ -190,7 +206,71 @@ class Agent(BaseAgent):
                                 if key not in ["prompt", "key_name", "default"]:
                                     # Only add default if the key is already set in os.environ
                                     if key in os.environ:
-                                        llm_params[key] = value
+                                        # Convert environment variables to proper types
+                                        try:
+                                            param_value = None
+                                            
+                                            # Integer parameters
+                                            if key in ['timeout', 'max_tokens', 'n', 'max_completion_tokens']:
+                                                try:
+                                                    param_value = int(str(value)) if value else None
+                                                except (ValueError, TypeError):
+                                                    continue
+                                                    
+                                            # Float parameters
+                                            elif key in ['temperature', 'top_p', 'presence_penalty', 'frequency_penalty']:
+                                                try:
+                                                    param_value = float(str(value)) if value else None
+                                                except (ValueError, TypeError):
+                                                    continue
+                                                    
+                                            # Boolean parameters
+                                            elif key == 'logprobs':
+                                                if isinstance(value, bool):
+                                                    param_value = value
+                                                elif isinstance(value, str):
+                                                    param_value = value.lower() == 'true'
+                                                    
+                                            # Dict parameters
+                                            elif key == 'logit_bias' and value:
+                                                try:
+                                                    if isinstance(value, dict):
+                                                        param_value = {int(k): float(v) for k, v in value.items()}
+                                                    elif isinstance(value, str):
+                                                        import json
+                                                        bias_dict = json.loads(value)
+                                                        param_value = {int(k): float(v) for k, v in bias_dict.items()}
+                                                except (ValueError, TypeError, json.JSONDecodeError):
+                                                    continue
+                                                    
+                                            elif key == 'response_format' and value:
+                                                try:
+                                                    if isinstance(value, dict):
+                                                        param_value = value
+                                                    elif isinstance(value, str):
+                                                        import json
+                                                        param_value = json.loads(value)
+                                                except (ValueError, json.JSONDecodeError):
+                                                    continue
+                                                    
+                                            # List parameters
+                                            elif key == 'callbacks':
+                                                if isinstance(value, (list, tuple)):
+                                                    param_value = list(value)
+                                                elif isinstance(value, str):
+                                                    param_value = [cb.strip() for cb in value.split(',') if cb.strip()]
+                                                else:
+                                                    param_value = []
+                                                    
+                                            # String and other parameters
+                                            else:
+                                                param_value = value
+
+                                            if param_value is not None:
+                                                llm_params[key] = param_value
+                                        except Exception:
+                                            # Skip any invalid values
+                                            continue
 
             self.llm = LLM(**llm_params)
         else:
diff --git a/tests/test_agent.py b/tests/test_agent.py
new file mode 100644
index 000000000..eaad771af
--- /dev/null
+++ b/tests/test_agent.py
@@ -0,0 +1,63 @@
+import os
+import pytest
+from unittest import mock
+
+from crewai.agent import Agent
+from crewai.llm import LLM
+
+def test_agent_with_custom_llm():
+    """Test creating an agent with a custom LLM."""
+    custom_llm = LLM(model="gpt-4")
+    agent = Agent()
+    agent.role = "test"
+    agent.goal = "test"
+    agent.backstory = "test"
+    agent.llm = custom_llm
+    agent.allow_delegation = False
+    agent.post_init_setup()
+    
+    assert isinstance(agent.llm, LLM)
+    assert agent.llm.model == "gpt-4"
+
+def test_agent_with_uppercase_llm_param():
+    """Test creating an agent with uppercase 'LLM' parameter."""
+    custom_llm = LLM(model="gpt-4")
+    with pytest.warns(DeprecationWarning):
+        agent = Agent()
+        agent.role = "test"
+        agent.goal = "test"
+        agent.backstory = "test"
+        setattr(agent, 'LLM', custom_llm)  # Using uppercase LLM
+        agent.allow_delegation = False
+        agent.post_init_setup()
+    
+    assert isinstance(agent.llm, LLM)
+    assert agent.llm.model == "gpt-4"
+    assert not hasattr(agent, 'LLM')
+
+def test_agent_llm_parameter_types():
+    """Test LLM parameter type handling."""
+    env_vars = {
+        "temperature": "0.7",
+        "max_tokens": "100",
+        "presence_penalty": "0.5",
+        "logprobs": "true",
+        "logit_bias": '{"50256": -100}',
+        "callbacks": "callback1,callback2",
+    }
+    with mock.patch.dict(os.environ, env_vars):
+        agent = Agent()
+        agent.role = "test"
+        agent.goal = "test"
+        agent.backstory = "test"
+        agent.llm = "gpt-4"
+        agent.allow_delegation = False
+        agent.post_init_setup()
+        
+        assert isinstance(agent.llm, LLM)
+        assert agent.llm.temperature == 0.7
+        assert agent.llm.max_tokens == 100
+        assert agent.llm.presence_penalty == 0.5
+        assert agent.llm.logprobs is True
+        assert agent.llm.logit_bias == {50256: -100.0}
+        assert agent.llm.callbacks == ["callback1", "callback2"]