Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations present, the description carries the full burden, and it discloses important behavioral traits: existing memories are updated in-place, re-indexed, duplicate entries are prevented, and new memories are created when no title matches. It stops short of describing permissions, irreversibility of the old text, or response details, but the core mutation and idempotence behavior is clearly communicated.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.