Wp-Cli Error

Does anyone have any experience using this? was following the roots blog to scaffold custom posts, but allI get is “Error: This does not seem to be a WordPress install.
Pass --path=path/to/wordpress or run wp core download.” it will then try and install wordpress inside the folder its already in by creating a new folder called wp-core. its like its not seeing the install. I just wondered if anyone else uses it and if so do they know what’s causing this?

Are you running “wp” inside the directory you have Wordpress installed to?

yes I am. even checked with ls, and its the right dir. im not sure if its something to do with the database, thats as far as i could fathom after trawling the web/