Which ancient Greek poem by Hesiod contains the most detailed account of Pandora's jar?

Hesiod's Works and Days contains the most detailed account of Pandora's jar.

Works and Days is a didactic poem concerned with farming, justice, labor, and the human condition. Within that broader work, Hesiod explains how Zeus's punishment after Prometheus's theft of fire brought suffering to humanity through Pandora and her container.

Hesiod's Theogony also mentions Pandora and related events, but Works and Days gives the fuller narrative sequence. It describes Pandora's creation, the gods' contributions, her arrival, and the opening of the jar. For that reason, references to the “Pandora's box” story usually point readers to Works and Days.

The Iliad and The Odyssey are Homeric epics and do not provide this detailed Pandora episode. Theogony is not irrelevant, but choosing it as the most detailed source misses the distinction between a brief related account and the expanded version in Works and Days.