Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It does disclose a genuinely non-obvious trait — history is appended, never rewritten — which tells the agent this is a non-destructive, history-preserving mutation. However it says nothing about whether transitions are validated (can DISCOVERED jump to OFFER?), required permissions, or any side effects.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.