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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: the data source, a paid model ($0.006 USDC per call via x402 across four chains), that compatible clients auto-pay, and a free sample path — material context for deciding whether calling is viable.

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?

Purpose and source are front-loaded, then indicators, then params, then payment, then a sample input. Dense but well-ordered; the payment and free-sample sentences add length but each carries actionable information.

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?

For a read-only data tool with no output schema and 0% schema description coverage, the description supplies the data source, all parameter semantics, cost model, and an example invocation. Nothing critical to calling it correctly is missing, though return structure is left unspecified.

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 0%, so the description must carry the burden, and it does: it documents all four params, adds non-obvious detail (country accepts ISO2 or ISO3, years range 1-20, indicator names, include_ecb_rates default). This adds real value over the bare schema, though it doesn't explain indicator units or behavior.

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 (country-level macroeconomic indicators) and data source (World Bank Open Data), enumerates the exact indicators covered, and distinguishes itself from siblings like crypto_prices or exchange_rates. An agent can tell immediately what this tool returns.

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 implied by the clear scope (macro indicators per country, optional ECB rates) and reinforced by a concrete sample input, but there is no explicit when-to-use/when-not guidance or named alternative. Adequate but with a clear gap in comparative routing.

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