Test Case
Configure a tool in a panel config like this
Code:
                tools: [{
                    iconCls: "x-fa fa-search",
                    ariaLabel : "YYY",
                    ariaLabelledBy : "XXX",
                    handler: function(origin){
                        //some code
                    }
                }],
Expected outcome
The tool gets some ARIA attribute (either "XXX", "YYY" or both) as described in the docs for Ext.Tool.ariaLabel and Ext.Tool.ariaLabelledBy

Actual outcome
No ARIA attribute is added to that tool

Fiddle
Test case in this Fiddle