Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does add real context: it enumerates what each service entry contains (partner counts, descriptions, required fields) and imposes a sandbox rule ('use fictitious data only. Do not enter real personal details'). It never explicitly states read-only behavior or failure modes, but 'List' plus the data constraint covers the key risks for a zero-param tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.