Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare destructiveHint=true and readOnlyHint=false, and the description goes well beyond that: it specifies that no further step starts, that a running command is stopped while a running file step or copy completes first, and that completed steps are not rolled back. This granular cancellation semantics and irreversibility disclosure is exactly the extra context annotations cannot carry.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.