Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations and no output schema, the description carries the full disclosure burden and does real work: it reveals the exact count (18), that each issue has two sides, that wording is deliberately partisan per side, and that sides carry short labels. What it omits is the concrete return structure (field names, how sides are nested), which would matter for parsing.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.