Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safe-read profile is covered. The description adds the "(API Pro)" tier requirement, which is useful beyond the annotations, but says nothing about pagination, result size, or what a missing birth time does to the ranking.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two compact sentences, front-loaded with the purpose and then the usage cue. No filler, though the parenthetical tier note is slightly awkwardly embedded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description does not need to explain return values, and annotations cover the safety profile. But for a tool with a required nested birth object and an unexplained limit parameter, the description leaves meaningful gaps an agent would have to resolve from the schema alone.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Top-level schema description coverage is 0%, so the description must compensate. It only alludes to two of four parameters ("life spheres" for focus and "region"), leaving limit and the entire required birth object unaddressed; the nested birth fields carry their own schema descriptions but the description adds nothing to them.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (ranks) and resource (major cities), and specifies scope: overall or by life spheres, worldwide or one region. It is clear on its own, but does not distinguish itself from the sibling location_score, which appears to be a related ranking tool.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

"Use it when the user asks where in the world to live, work or travel" gives a clear triggering context. However, it names no exclusions and does not route the agent away from the plausibly overlapping location_score or best_days siblings.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.