Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries behavioral burden. It discloses data provenance ('local Perplexity-sourced dataset'), output concept ('Bullish/Bearish/Neutral + numeric score'), and a constraint ('lookback_days ... max 90'). It does not explicitly state read-only behavior or failure modes, but the context implies a safe read operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.