Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It states that role and message indexes are preserved, which is a positive behavioral trait. However, it does not disclose whether the tool modifies data, requires authentication, or has side effects, leaving significant behavioral gaps.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.