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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so safety is covered. The description adds genuinely new behavioral context beyond the annotations: the pricing model ('free within the daily allowance, then $0.002 USDC per call via x402'), which is exactly the kind of cost/call-limit disclosure an agent needs before invoking.

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?

Two tight sentences with no filler; the resource and its returned fields are front-loaded before the pricing note. Nothing is wasted, though it is terse enough that a slightly richer usage clause would have fit.

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?

An output schema exists, so return values need not be explained, and annotations cover the safety profile. The description adds the cost/allowance behavior. It is essentially complete for a read-only lookup tool, with only the absence of alternative-routing guidance keeping it from the top.

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 description coverage is 100%, so the schema already documents page, status, country and order_number. The description restates the country and order-number filters and enumerates status values, but adds no syntax or format detail beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 names the specific resource (tariff-rate quota definitions) and enumerates the data returned (status, initial volume, remaining balance, validity), which is more concrete than a bare title restatement. It also states the two lookup keys (order number, country of origin). It does not explicitly differentiate itself from sibling tariff tools like commodity or heading, but the resource is unambiguous.

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 is implied by the filtering keys ('by order number or country of origin'), so an agent can infer when to reach for it. However, no when-to-use/when-not guidance, no prerequisites, and no named alternative (e.g. vs uk-trade-tariff__commodity) are given.

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