Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Goes well beyond the annotations by disclosing all four terminal/pending states, the fact that the device code is single-use and a second poll reports 'expired', the scope of the resulting access (mirrors the human's existing tier, no agent-only privilege), revocation via Account Security, and secret-handling rules for session_token.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.