Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral disclosure burden. It discloses that comparison is line-by-line and that the return includes added/removed/unchanged counts and diff output. This gives an agent a reasonable expectation of the tool's behavior, though it does not cover edge cases like whitespace handling or exact diff formatting.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.