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

Annotations only cover the safety profile (readOnly, openWorld, idempotent, non-destructive), so the description carries behavior beyond them: the $0.25 charge, the x402 fallback when no api_key is passed, the free refusal path, the shared daily rate limit, the optional receipt behavior, and the verification path. It also flags a legal caveat, which is unusually informative for an agent deciding to invoke.

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?

It front-loads the key fact ('PAID ($0.25)'), but the body is one dense run-on packed with parenthetical asides, price mentions, and cross-references that make it hard to parse on a first read. Most sentences carry information, yet the structure works against 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?

Given an output schema exists, the description does not need to explain returns, and it covers payment, refusal, receipts, and verification thoroughly. The remaining gap is that it never clarifies how the bundled brief relates to the standalone get_country_brief sibling.

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, but the description adds real semantics on top: series defaults to 'the first certifiable of vat, policy-rate, minimum-wage', series must all be certifiable, api_key is metered for invoicing, and receipt is no-cost on paid success only. These details are not in the schema text.

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 artifact: 'the full cited country brief plus up to 3 Ed25519-signed certified extracts', which tells an agent exactly what is produced. It is clear and concrete, but it never explicitly distinguishes itself from the sibling get_country_brief or charge_sale_certified, which appear to overlap in scope.

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?

It gives strong preconditions ('Named series must all be certifiable'), the payment path (api_key or x402 requirement), and the free-refusal condition (coverage_gap, no_charge), and it notes the shared 3 free calls per IP with the answer tools, implying those siblings as alternatives. It stops short of an explicit 'use X instead when Y' routing statement.

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