Add instructions field to ServerSession and FastMCP

tests/client/test_session.py

@@ -51,7 +51,7 @@ async def test_client_session_initialize():
                     prompts=None,
                 ),
                 serverInfo=Implementation(name="mock-server", version="0.1.0"),
-                instructions="The server instructions."
+                instructions="The server instructions.",
             )
         )
 

tests/server/fastmcp/test_server.py

@@ -27,8 +27,9 @@ if TYPE_CHECKING:
 class TestServer:
     @pytest.mark.anyio
     async def test_create_server(self):
-        mcp = FastMCP()
+        mcp = FastMCP(instructions="Server instructions")
         assert mcp.name == "FastMCP"
+        assert mcp.instructions == "Server instructions"
 
     @pytest.mark.anyio
     async def test_non_ascii_description(self):