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

Annotations only say readOnly and open-world; the description adds materially important behavior an agent cannot infer: a $0.002 USDC charge per successful call, x402 payment on Base/Solana/Arc, and that failed calls are free. It also discloses a source-coverage limitation (no contract-award notices), which prevents misuse.

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?

Three compact sentences: what it returns, what it does not cover, and what it costs — all front-loaded with the resource first. The field enumeration could duplicate the output schema, but it is short and aids tool selection rather than padding.

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 two-parameter read tool with an output schema and light annotations, the description covers purpose, source limitation, and the pay-per-call billing requirement — the latter being the highest-risk unknown. Nothing needed to invoke 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?

Schema coverage is 100% and both parameters (country as ISO 2-letter code, rows 1-20 default 5) are fully documented in the schema. The description adds no format, default, or range information beyond what is already structured, so baseline 3 applies.

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 verb+resource ('World Bank funded projects by country from the World Bank Projects API') and enumerates the returned fields (project name, status, total amount, approval year, project page). The clause 'Project list only; contract-award notices are not in this source' separates it from the procurement-notice siblings without ambiguity.

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 exclusion ('project list only, contract-award notices are not in this source') tells the agent when NOT to use it and implicitly routes notice lookups elsewhere. It stops short of naming the alternative sibling (e.g. energy_adb_procurement_notices) or stating the positive trigger condition, so it is clear context but not a full when/when-not/alternatives triad.

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