Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish readOnlyHint=true, so safety is covered. The description adds non-obvious behavioral context: the source is wrapped in each platform's runtime shell before formatting to handle top-level await, bare return, and injected globals, and that output includes lint diagnostics. It does not mention size limits (only in schema) or how severe/format of diagnostics appear.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.