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 genuinely non-derivable behavior: a $0.002 USDC charge per successful call billed via x402 on Base/Solana/Arc, and that failed calls are not charged. That is exactly the kind of cost/authorization context structured fields don't carry. It does not explain error behavior for a non-matching agency name or result ordering beyond 'largest'.

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 purpose and scope, then constraints, then pricing — no filler sentences. Slight redundancy in listing returned fields that the output schema already defines, and the phrase 'one toptier awarding agency' is awkward, but overall it is tight and information-dense.

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 an output schema (so return values needn't be spelled out) and annotations covering read-only/open-world, the description supplies the remaining essentials: source, contract-only scope, lookback bounds, toptier-name requirement, and cost model. Only minor gaps remain — behavior on an unmatched agency and any result ordering/pagination detail beyond 'largest'.

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%, so the baseline is 3, and the description still adds meaning: it clarifies that results are the 'largest' awards (implicit ordering by amount), that the range must be 1-365 days, and that 'agency' must be a USAspending toptier name — a stricter requirement than the schema's 'e.g. Department of Defense'. The limit parameter's bounds are left entirely to the schema.

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+source: largest US federal contract awards from USAspending.gov for a single toptier awarding agency, with an explicit lookback range and the four returned fields. Scope is narrow and concrete ('contracts only'), so it is distinguishable in practice, but it never names or contrasts the closely-related sibling gov_government_contract_awards, leaving the agent to infer the difference.

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?

Provides a real prerequisite ('agency name must match USAspending's toptier name') and implies usage from the description ('Contracts only'), which is useful. However it gives no explicit when-to-use/when-not guidance and never points to an alternative tool for similar contract-award or tender queries despite many gov_* siblings.

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