diff --git a/tests/test_models.py b/tests/test_models.py
new file mode 100644
index 0000000..2f6a7da
--- /dev/null
+++ b/tests/test_models.py
@@ -0,0 +1,202 @@
+"""Tests for MCP protocol message models."""
+
+import pytest
+from pydantic import ValidationError
+
+from mcp_server_cli.models import (
+    MCPRequest,
+    MCPResponse,
+    MCPNotification,
+    MCPMethod,
+    ToolDefinition,
+    ToolSchema,
+    ToolParameter,
+    ToolCallParams,
+    ToolCallResult,
+    InitializeParams,
+    InitializeResult,
+    ServerConfig,
+    LocalLLMConfig,
+    SecurityConfig,
+    AppConfig,
+)
+
+
+class TestMCPRequest:
+    """Tests for MCPRequest model."""
+
+    def test_create_request(self):
+        """Test creating a basic request."""
+        request = MCPRequest(
+            id=1,
+            method=MCPMethod.INITIALIZE,
+            params={"protocol_version": "2024-11-05"},
+        )
+        assert request.jsonrpc == "2.0"
+        assert request.id == 1
+        assert request.method == MCPMethod.INITIALIZE
+        assert request.params["protocol_version"] == "2024-11-05"
+
+    def test_request_without_id(self):
+        """Test request without id (notification)."""
+        request = MCPRequest(
+            method=MCPMethod.TOOLS_LIST,
+        )
+        assert request.id is None
+        assert request.method == MCPMethod.TOOLS_LIST
+
+
+class TestMCPResponse:
+    """Tests for MCPResponse model."""
+
+    def test_create_response_with_result(self):
+        """Test creating a response with result."""
+        response = MCPResponse(
+            id=1,
+            result={"tools": [{"name": "test_tool"}]},
+        )
+        assert response.jsonrpc == "2.0"
+        assert response.id == 1
+        assert response.result["tools"][0]["name"] == "test_tool"
+
+    def test_create_response_with_error(self):
+        """Test creating a response with error."""
+        response = MCPResponse(
+            id=1,
+            error={"code": -32600, "message": "Invalid Request"},
+        )
+        assert response.error["code"] == -32600
+        assert response.error["message"] == "Invalid Request"
+
+
+class TestToolModels:
+    """Tests for tool-related models."""
+
+    def test_tool_definition(self):
+        """Test creating a tool definition."""
+        tool = ToolDefinition(
+            name="read_file",
+            description="Read a file from disk",
+            input_schema=ToolSchema(
+                properties={
+                    "path": ToolParameter(
+                        name="path",
+                        type="string",
+                        description="File path",
+                        required=True,
+                    )
+                },
+                required=["path"],
+            ),
+        )
+        assert tool.name == "read_file"
+        assert "path" in tool.input_schema.required
+
+    def test_tool_name_validation(self):
+        """Test that tool names must be valid identifiers."""
+        with pytest.raises(ValidationError):
+            ToolDefinition(
+                name="invalid-name",
+                description="Tool with invalid name",
+            )
+
+    def test_tool_parameter_with_enum(self):
+        """Test tool parameter with enum values."""
+        param = ToolParameter(
+            name="operation",
+            type="string",
+            enum=["read", "write", "delete"],
+        )
+        assert param.enum == ["read", "write", "delete"]
+
+
+class TestConfigModels:
+    """Tests for configuration models."""
+
+    def test_server_config_defaults(self):
+        """Test server config default values."""
+        config = ServerConfig()
+        assert config.host == "127.0.0.1"
+        assert config.port == 3000
+        assert config.log_level == "INFO"
+
+    def test_local_llm_config_defaults(self):
+        """Test local LLM config defaults."""
+        config = LocalLLMConfig()
+        assert config.enabled is False
+        assert config.base_url == "http://localhost:11434"
+        assert config.model == "llama2"
+
+    def test_security_config_defaults(self):
+        """Test security config defaults."""
+        config = SecurityConfig()
+        assert "ls" in config.allowed_commands
+        assert "/etc" in config.blocked_paths
+        assert config.max_shell_timeout == 30
+
+    def test_app_config_composition(self):
+        """Test app config with all components."""
+        config = AppConfig(
+            server=ServerConfig(port=8080),
+            llm=LocalLLMConfig(enabled=True),
+            security=SecurityConfig(allowed_commands=["echo"]),
+        )
+        assert config.server.port == 8080
+        assert config.llm.enabled is True
+        assert "echo" in config.security.allowed_commands
+
+
+class TestToolCallModels:
+    """Tests for tool call models."""
+
+    def test_tool_call_params(self):
+        """Test tool call parameters."""
+        params = ToolCallParams(
+            name="read_file",
+            arguments={"path": "/tmp/test.txt"},
+        )
+        assert params.name == "read_file"
+        assert params.arguments["path"] == "/tmp/test.txt"
+
+    def test_tool_call_result(self):
+        """Test tool call result."""
+        result = ToolCallResult(
+            content=[{"type": "text", "text": "Hello"}],
+            is_error=False,
+        )
+        assert result.content[0]["text"] == "Hello"
+        assert result.is_error is False
+
+    def test_tool_call_result_error(self):
+        """Test tool call result with error."""
+        result = ToolCallResult(
+            content=[],
+            is_error=True,
+            error_message="File not found",
+        )
+        assert result.is_error is True
+        assert result.error_message == "File not found"
+
+
+class TestInitializeModels:
+    """Tests for initialize-related models."""
+
+    def test_initialize_params(self):
+        """Test initialize parameters."""
+        params = InitializeParams(
+            protocol_version="2024-11-05",
+            capabilities={"tools": {}},
+            client_info={"name": "test-client"},
+        )
+        assert params.protocol_version == "2024-11-05"
+        assert params.client_info["name"] == "test-client"
+
+    def test_initialize_result(self):
+        """Test initialize result."""
+        result = InitializeResult(
+            protocol_version="2024-11-05",
+            server_info={"name": "mcp-server", "version": "0.1.0"},
+            capabilities={"tools": {"listChanged": True}},
+        )
+        assert result.server_info.name == "mcp-server"
+        assert result.capabilities.tools["listChanged"] is True