Added mcp 'instructions' attribute to the server (#706)

Added the `instructions` attribute to the MCP servers to solve #704 .

Let me know if you want to add an example to the documentation.

Author: DanieleMorotti

src/agents/mcp/server.py

@@ -12,7 +12,7 @@
 from mcp.client.sse import sse_client
 from mcp.client.streamable_http import GetSessionIdCallback, streamablehttp_client
 from mcp.shared.message import SessionMessage
-from mcp.types import CallToolResult
+from mcp.types import CallToolResult, InitializeResult
 from typing_extensions import NotRequired, TypedDict
 
 from ..exceptions import UserError
@@ -73,6 +73,7 @@ def __init__(self, cache_tools_list: bool, client_session_timeout_seconds: float
         self.exit_stack: AsyncExitStack = AsyncExitStack()
         self._cleanup_lock: asyncio.Lock = asyncio.Lock()
         self.cache_tools_list = cache_tools_list
+        self.server_initialize_result: InitializeResult | None = None
 
         self.client_session_timeout_seconds = client_session_timeout_seconds
 
@@ -122,7 +123,8 @@ async def connect(self):
                     else None,
                 )
             )
-            await session.initialize()
+            server_result = await session.initialize()
+            self.server_initialize_result = server_result
             self.session = session
         except Exception as e:
             logger.error(f"Error initializing MCP server: {e}")