Block harvest level setting has no effect

1.12.2-forge1.12.2-14.23.1.2555
BlockTweaker-1.0.0.jar

Vanilla block harvest level does not seem to affect harvest-ability of blocks.
Default harvest level for all blocks in config is 0 (wood) but will allow harvesting with fist. Setting harvest level higher does not prevent harvesting with fist or another lower level tool.
I have only tested with clay and "wood" (may want to rename to wood log for easier ctrl+f through config file).

Behavior I hoped to see would be for blocks to break slower, but drop no resources, if not mined with the tool level set in the config, similar to stone or coal ore.