Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It usefully discloses that the output is links rather than data, and that the underlying Bing tools have no public API. However, it says nothing about whether Bing Webmaster Tools authentication is required to follow those links, whether results vary per site, or what the response format looks like beyond 'links'.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.