on the tools

Prepositional phrase

Doing manual labour as a tradesperson, as opposed to being a foreman, business owner, etc., in the industry.

Japanese Meaning

現場で実際に肉体労働を行う、監督や管理者ではなく実働者として働くこと / 熟練労働者として現場で直接作業を行う状態 / 手作業で作業する技術者として、指導的立場ではなく現役として働くこと

Even after earning his certification, he stayed on the tools to gain more practical experience.

認定を取得した後も、彼はさらに実務経験を積むために職人として現場で働き続けた。

Sense（1）

Doing manual labour as a tradesperson, as opposed to being a foreman, business owner, etc., in the industry.

The successful applicant will not be afraid to work with the men "on the tools", so that he knows them, can motivate them, and lead them by example.