Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, so the description must compensate, and it does: 'exact key' adds match semantics and 'the key you wrote earlier' ties the parameter to a prior memory_set call. The schema only provides type and length constraints, so the description meaningfully enriches the meaning of the single parameter.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.