Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false, destructiveHint=false, and non-idempotency, and the description adds genuinely new context: the table is real, the human plays on the website, the first joiner becomes host, and the tool must never bet or play on the user's behalf. That hosting rule is exactly the kind of side-effect nuance annotations cannot express. It stops short of disclosing what happens on repeated calls or table lifetime limits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.