Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds value beyond the read-only and idempotent annotations by specifying the exact output content (relation type and confidence of each edge). This gives the agent a concrete expectation of what the tool returns, though it omits any potential edge cases like pagination or limits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.