Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint=false and destructiveHint=false, so safety profile is already covered. The description adds real value beyond that: it discloses the source-side effect ('Increments the source's fork counter') and the permission rule (public/unlisted any, private only if owned).
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.