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

Annotations cover the safety profile (readOnly, idempotent, openWorld, non-destructive), and the description layers on substantial extra behavior: the $0.50 price, the free-refusal policy, the IP rate limit, the api_key/x402 auth paths, the optional Ed25519 receipt (and that it is not a certified extract or legal advice), and the verify_answer_receipt follow-up. This is well beyond what structured fields provide.

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 purpose is front-loaded and every clause is informative, but the text is a dense block mixing pricing, payment, receipt, certified-extract, and legal-advice caveats. The receipt/certified-extract disclaimer is repeated between description and schema, and the caveat tail could be tightened without losing any actionable detail.

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?

With an output schema present and 100% parameter coverage, return values and field-level syntax don't need restating, and the description does supply the payment model, refusal semantics, supported countries, and receipt flow. It's comprehensive for a paid, multi-country computation tool; only sibling disambiguation is absent.

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 meaning: it explains that receipt defaults to false and yields an Ed25519 answer receipt only on a paid success, and it clarifies purpose for taxable_income (applies the income-tax schedule), start_date (first working day on or after), and hours_per_week (hourly wage-floor check). The api_key-versus-x402 behavior is also described only in prose, not 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?

The description states a specific verb+resource ('Cost this hire') and enumerates the output ('wage-floor verdict, employer and employee contributions..., employer cost, optional income tax...'), so an agent knows exactly what it produces. It also names the served countries (DE, ES, GB, IT, PL). However, it never differentiates itself from close siblings like compute_employment_cost, hire_compare, or check_minimum_wage, leaving the agent to infer which one applies.

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?

Usage context is clear: pass api_key or fall back to the x402 payment requirement, three free calls per IP per day shared with the answer tools, and unpaid/incomplete requests are refused free with coverage_gap. What's missing is explicit routing versus the sibling cost/wage tools, so the agent gets when but not 'when instead of compute_employment_cost'.

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