Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already declare readOnlyHint=true, and the description reinforces this by stating 'read-only — computes shades, changes nothing.' It adds the detail that the tool computes shades, which is valuable behavioral context beyond the annotation. Given the tool's simplicity and the existing annotation coverage, this is sufficient.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.