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

With no annotations, the description carries the full burden and does disclose the critical non-obvious behavior: the call costs $0.005 USDC on Base via x402, which affects whether an agent should invoke it. It also clarifies that each metric comes with current year, previous year and change, so the caller knows the shape of the mutating-free lookup. It omits error/failure behavior for unrecognized countries and any rate limits.

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?

Front-loaded with the core resource and metric list, then a short second sentence covering the payment requirement. The long metric enumeration is information-dense rather than padding, though it could be grouped (e.g. 'GDP variants, inflation, unemployment, demographics, external sector') for faster scanning.

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?

No output schema exists, so the description must convey return content, and it does so thoroughly (metric list, year/previous/change structure, region/income/capital). Payment cost is also covered. Missing only edge details an agent might want: what happens for an unknown country, and how fresh the underlying data is beyond 'latest year'.

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 coverage is 100% and the single parameter already documents ISO-code-or-name acceptance with a pattern constraint, so the description adds no parameter-level meaning. Baseline 3 applies since the schema does the work.

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 resource (World Bank headline economics for a country) and enumerates the metrics returned, plus supplementary fields (region, income level, capital). An agent can tell immediately this is a macro-economic country lookup, distinct from every sibling (crypto, company, FX, jobs tools).

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?

Usage is only implied by the data domain; there is no explicit when-to-use, when-not-to-use, or pointer to alternatives. In practice there is no close sibling for macro data, so the practical risk is low, but the description itself provides no routing guidance.

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