Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. While 'Update' implies a mutation operation, the description doesn't address critical behavioral aspects like whether this requires specific permissions, what happens if some updates fail, whether changes are reversible, or any rate limits. The mention of 'multiple contacts' hints at batch behavior but lacks operational details.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.