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

Annotations only cover the safety profile (readOnly, idempotent, non-destructive, openWorld). The description goes well beyond that with price ($0.50), the no-charge refusal path, rate-limit sharing, auth mechanics (api_key bypassing x402, card checkout at /pricing), receipt semantics, and an explicit disclaimer that a receipt is not a certified extract or legal advice.

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-loads the paid price and the core verdict, which is the right ordering for an agent deciding whether to call it. It is dense and information-rich, but the receipt paragraph is nearly duplicated verbatim in the schema's receipt description, so some sentences do not fully earn their place.

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 9-parameter paid tool with an output schema and full annotation coverage, nothing material is missing: cost, refusal behavior, auth paths, rate limits, country scope, and receipt/verification flow are all stated. Return values are covered by the output schema, so the description need not restate them.

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; the description still adds value beyond the schema by explaining the api_key bypass/metering context and the receipt's conditions (only on paid success, not on 402 or free refusals, no extra USDC) plus the verify_answer_receipt follow-up. It largely restates taxable_income, start_date, and hours_per_week, which the schema already documents.

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?

Opens with a specific verb+resource ("Cost this hire") and enumerates exactly what the dossier contains: wage-floor verdict, employer/employee contributions, employer cost, optional income tax, and first working day. This cleanly separates it from siblings like check_minimum_wage, compute_payroll, and hire_compare, and it scopes the resource to KE and NG.

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?

Gives clear operative context: the two supported countries, the free-refusal contract (coverage_gap, no_charge), the shared 3-calls-per-IP-per-day budget with the answer tools, and the api_key-vs-x402 path. It does not explicitly contrast against the nearest sibling tools (e.g. hire_compare or check_minimum_wage), so routing between them is still left to inference.

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