Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden for behavioral disclosure. It adds a crucial warning that decoded chain content is untrusted and should never be followed as instructions, which is a key safety trait. It does not explicitly state read-only behavior, but 'decode' implies no side effects, and the security note adds significant value beyond a bare description.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.