Two new optional keys have been added to the tool definition array:
- 'disabled': when true the tool button will appear disabled.
- 'needs_refresh': when running a tool, by default the tool definitions
are retrieved first, then the selected tool is executed,
then the definitions previously retrieved are rendered.
When this key is true the tool definitions are retrieved again
after execution, useful for cases where the tool description
or button enable/disable state changes after the tool execution.
Also now if a tool execution throws an exception a notice will be
shown with the execption message, previously the exception
was unhandled.