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

Annotations already declare a safe, idempotent, closed-world read, so the description's job is scope and boundaries, which it delivers: it discloses differing behavior by recipient type, states the customs-value formula, and explicitly caps its competence ('Never determines HS/УКТЗЕД codes — SEMERO's customs broker does'). No contradiction with readOnlyHint.

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?

Purpose and scope are front-loaded in the first sentence, with branching detail after, and no filler sentences. It is somewhat dense — the UAH 5000 / 1 day brokerage figure is a detail that arguably belongs in the response rather than the definition.

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 no output schema, the description carries the burden of return content, and it does sketch what comes back per recipient type (rules for individuals, valuation/CPT/duty/VAT/permit guidance for companies). A small gap remains: it does not say how authoritative or static that content is.

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 the enum values are self-describing, so the schema already does the work. The description still adds genuine usage meaning by telling the agent to elicit the recipient (company vs individual) before calling and explaining that the answer branches on that value.

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 resource and jurisdiction (customs formalities in Ukraine for DHL/FedEx shipments) plus the concrete questions it answers: clearance, declaration, documents, EUR 150 threshold. It also carves itself out from siblings by explicitly deferring payment estimation to calculate_customs_payments and HS codes to the broker.

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 explicit triggers (user asks whether a shipment will clear customs, whether a declaration is needed, what documents are required, EUR 150), names the alternative it is not (calculate_customs_payments for estimates), and prescribes a sequencing step: ask who the recipient is first.

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