If you have the required tools to craft an item have them automatically added to the tool slots. However still allow the player to switch them around with a different tool of the same type should they so wish as I assume tools will have qualities and durability at a later date and as such a player may have more than one of a tool in his pack but wish to use a specific one.
I'd like to expand on this suggestion. If you have the required tool, or resource, let it show up in the boxes. If you have multiple options, clicking on the tool or resource should give a drop-down option box with all of the items you could possibly use. I did a little grass weaving today and I found it rather tedious having to drag things across the screen for each craft action.