Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already declare readOnlyHint and openWorldHint, and the description adds no behavioral context beyond the word 'subscribe'. It does not disclose whether the call returns after timeoutMs or messageCount, whether the subscription is one-shot or continuous, or what the orderbook stream actually contains.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.