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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds meaningful behavioral context beyond annotations: per-call pricing of $0.002 USDC via x402 on Base, Solana or Arc, and the fact that failed calls are not charged.

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 front-loaded with the tool's purpose and packs relevant valuation and pricing details into two sentences. It is dense but appropriate for a financial-data endpoint; a minor deduction for the long currency-list clause.

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?

Given the tool takes no parameters and has an output schema, the description is complete enough: it identifies the data source, the valuation date convention, the basket composition, the conversion formulas, and the pricing model. Nothing an agent needs in order to call it correctly is missing.

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?

This tool has zero parameters, so the baseline score is 4. There are no parameter semantics to explain, and schema coverage is irrelevant for an empty input object.

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 states a specific resource and scope: IMF Special Drawing Rights valuation for the latest IMF business day, with detailed breakdowns of basket currencies and SDR/USD conversions. It is clearly distinct from the sibling exchange-rate and commodity tools, though it does not explicitly name an alternative for comparison.

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?

The description explains what the tool returns but gives no explicit guidance on when to use it versus alternatives such as energy_bis_effective_exchange_rate or other FX-related siblings. Usage context is only implied by the tool's purpose and the 'latest IMF business day' scope.

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