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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuinely new behavioral context the annotations do not carry: a per-call cost of $0.002 USDC and the x402 payment mechanism, which materially affects whether an agent should invoke it.

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 sentences, front-loaded with the core data payload and closing with the cost. The indicator list is long but each item is a distinct return field, so it earns its space; a tighter grouping could have saved a few words.

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 carries the full burden of describing returns, and it does so comprehensively by enumerating every profile field and indicator. Pricing and input form are also covered, leaving little an agent would need before calling.

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?

Schema description coverage is 0% and the single 'q' parameter is undocumented in the schema, so the burden falls on the description. It does compensate by stating the accepted forms ('name or ISO code'), the one thing an agent needs to pass correctly, though it gives no format examples for ambiguous cases.

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?

The description names a specific resource (country profile) with a clear input form (name or ISO code) and enumerates the exact payload (capital, region, World Bank indicators), which is far more concrete than the sibling 'demographics' or 'economy' entries. It does not explicitly differentiate itself from those overlapping siblings, so it stops short of a 5.

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?

There is no statement of when to use this tool versus the many overlapping siblings (demographics, demographics_area, economy, macro_us, labor). The phrase 'by name or ISO code' implies the input form only; no alternatives or exclusions are offered.

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