Briefly talk about how the poet's mood is expressed in the details of the action of "knocking chess pieces at random"

Because you can't play chess by yourself, you can say "knock on the chess pieces". Chess pieces are not for knocking, but for knocking, reflecting the anguish in loneliness; The word "leisure" expresses boredom, and behind this word, the poet's disappointment and anxiety are implied.

When people are lonely and anxious, they often subconsciously make a monotonous and mechanical action, such as deliberately making a noise to break the silence and dilute their worries. The poet's "knocking chess pieces" here is just such an action.