refactor: modernize type hints and improve async context handling

- Update type hints to use Python 3.10 syntax (dict, list, X | None)
- Replace requests with httpx for HTTP client consistency
- Improve async context management using AsyncExitStack
- Simplify server cleanup method

examples/clients/simple-chatbot/mcp_simple_chatbot/main.py

@@ -3,9 +3,10 @@ import json
 import logging
 import os
 import shutil
-from typing import Any, Dict, List, Optional
+from contextlib import AsyncExitStack
+from typing import Any
 
-import requests
+import httpx
 from dotenv import load_dotenv
 from mcp import ClientSession, StdioServerParameters
 from mcp.client.stdio import stdio_client
@@ -30,7 +31,7 @@ class Configuration:
         load_dotenv()
 
     @staticmethod
-    def load_config(file_path: str) -> Dict[str, Any]:
+    def load_config(file_path: str) -> dict[str, Any]:
         """Load server configuration from JSON file.
 
         Args:
@@ -64,12 +65,13 @@ class Configuration:
 class Server:
     """Manages MCP server connections and tool execution."""
 
-    def __init__(self, name: str, config: Dict[str, Any]) -> None:
+    def __init__(self, name: str, config: dict[str, Any]) -> None:
         self.name: str = name
-        self.config: Dict[str, Any] = config
-        self.stdio_context: Optional[Any] = None
-        self.session: Optional[ClientSession] = None
+        self.config: dict[str, Any] = config
+        self.stdio_context: Any | None = None
+        self.session: ClientSession | None = None
         self._cleanup_lock: asyncio.Lock = asyncio.Lock()
+        self.exit_stack: AsyncExitStack = AsyncExitStack()
 
     async def initialize(self) -> None:
         """Initialize the server connection."""
@@ -89,17 +91,16 @@ class Server:
             else None,
         )
         try:
-            self.stdio_context = stdio_client(server_params)
-            read, write = await self.stdio_context.__aenter__()
-            self.session = ClientSession(read, write)
-            await self.session.__aenter__()
+            stdio_transport = await self.exit_stack.enter_async_context(stdio_client(server_params))
+            read, write = stdio_transport
+            self.session = await self.exit_stack.enter_async_context(ClientSession(read, write))
             await self.session.initialize()
         except Exception as e:
             logging.error(f"Error initializing server {self.name}: {e}")
             await self.cleanup()
             raise
 
-    async def list_tools(self) -> List[Any]:
+    async def list_tools(self) -> list[Any]:
         """List available tools from the server.
 
         Returns:
@@ -124,7 +125,7 @@ class Server:
     async def execute_tool(
         self,
         tool_name: str,
-        arguments: Dict[str, Any],
+        arguments: dict[str, Any],
         retries: int = 2,
         delay: float = 1.0,
     ) -> Any:
@@ -170,29 +171,9 @@ class Server:
         """Clean up server resources."""
         async with self._cleanup_lock:
             try:
-                if self.session:
-                    try:
-                        await self.session.__aexit__(None, None, None)
-                    except Exception as e:
-                        logging.warning(
-                            f"Warning during session cleanup for {self.name}: {e}"
-                        )
-                    finally:
-                        self.session = None
-
-                if self.stdio_context:
-                    try:
-                        await self.stdio_context.__aexit__(None, None, None)
-                    except (RuntimeError, asyncio.CancelledError) as e:
-                        logging.info(
-                            f"Note: Normal shutdown message for {self.name}: {e}"
-                        )
-                    except Exception as e:
-                        logging.warning(
-                            f"Warning during stdio cleanup for {self.name}: {e}"
-                        )
-                    finally:
-                        self.stdio_context = None
+                await self.exit_stack.aclose()
+                self.session = None
+                self.stdio_context = None
             except Exception as e:
                 logging.error(f"Error during cleanup of server {self.name}: {e}")
 
@@ -201,11 +182,11 @@ class Tool:
     """Represents a tool with its properties and formatting."""
 
     def __init__(
-        self, name: str, description: str, input_schema: Dict[str, Any]
+        self, name: str, description: str, input_schema: dict[str, Any]
     ) -> None:
         self.name: str = name
         self.description: str = description
-        self.input_schema: Dict[str, Any] = input_schema
+        self.input_schema: dict[str, Any] = input_schema
 
     def format_for_llm(self) -> str:
         """Format tool information for LLM.
@@ -237,7 +218,7 @@ class LLMClient:
     def __init__(self, api_key: str) -> None:
         self.api_key: str = api_key
 
-    def get_response(self, messages: List[Dict[str, str]]) -> str:
+    def get_response(self, messages: list[dict[str, str]]) -> str:
         """Get a response from the LLM.
 
         Args:
@@ -247,7 +228,7 @@ class LLMClient:
             The LLM's response as a string.
 
         Raises:
-            RequestException: If the request to the LLM fails.
+            httpx.RequestError: If the request to the LLM fails.
         """
         url = "https://api.groq.com/openai/v1/chat/completions"
 
@@ -266,16 +247,17 @@ class LLMClient:
         }
 
         try:
-            response = requests.post(url, headers=headers, json=payload)
-            response.raise_for_status()
-            data = response.json()
-            return data["choices"][0]["message"]["content"]
+            with httpx.Client() as client:
+                response = client.post(url, headers=headers, json=payload)
+                response.raise_for_status()
+                data = response.json()
+                return data["choices"][0]["message"]["content"]
 
-        except requests.exceptions.RequestException as e:
+        except httpx.RequestError as e:
             error_message = f"Error getting LLM response: {str(e)}"
             logging.error(error_message)
 
-            if e.response is not None:
+            if hasattr(e, 'response'):
                 status_code = e.response.status_code
                 logging.error(f"Status code: {status_code}")
                 logging.error(f"Response details: {e.response.text}")
@@ -289,8 +271,8 @@ class LLMClient:
 class ChatSession:
     """Orchestrates the interaction between user, LLM, and tools."""
 
-    def __init__(self, servers: List[Server], llm_client: LLMClient) -> None:
-        self.servers: List[Server] = servers
+    def __init__(self, servers: list[Server], llm_client: LLMClient) -> None:
+        self.servers: list[Server] = servers
         self.llm_client: LLMClient = llm_client
 
     async def cleanup_servers(self) -> None: