Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden of behavioral disclosure. It reveals the content type (guidelines) and adds a crucial behavioral nuance: 'the standard is stricter than the endpoint's own validation', which warns users about stricter expectations. It does not mention return format or potential errors, but for a read-only guideline tool, 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.