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

With no annotations, the description carries the behavioral burden. It discloses cost ('Free (0c)', 'Price: 0¢ per call') and implies a read-only list operation, but it does not explicitly state that the call has no side effects or describe rate limits beyond what the output schema already provides.

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?

The description is short and front-loaded, but it repeats the cost ('Free (0c)' and '**Price: 0¢ per call.**'), so not every sentence earns its place. Removing one of the price statements would make it tight.

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?

The output schema and 100% parameter coverage cover the return shape and parameters, so the description only needs to supply cost and the key use case. It does that, though the '/values' reference is slightly indirect compared to naming the sibling tool area_stats_values.

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?

Input schema already documents all three parameters (100% coverage), so the baseline applies. The description adds little parameter-specific detail; 'exact region names to pass to /values' clarifies the purpose of the output but not the parameters themselves.

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 the action ('List'), the resource ('regions that exist at a level'), and the scope ('every suburb, LGA, postcode, etc.'). It also points to the downstream use ('pass to /values'), which differentiates it from area_stats_values without needing to open that tool's schema.

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?

Explicitly tells the agent when to call it: to discover exact region names to pass to /values. It does not spell out exclusions or name alternative tools, but the intended context is clear enough for routing.

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