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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds value beyond them by confirming 'Charges nothing' (a cost behavior annotations cannot express) and by naming the return field orderPriceCents, which matters because no output schema exists.

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 tightly packed sentences with zero filler; the scope and the cost/return facts are front-loaded where an agent will read them first.

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 three-param, no-output-schema read tool, it covers scope, validation constraints, cost, and the key return field. Only the full shape of the quote response is left unstated, which is a minor gap given the key field is disclosed.

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 genuinely adds semantics the schema omits: the range is inclusive UTC days, must meet a minimum length, and must fall inside the days on sale. Those are real calling constraints, not restatements.

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 verb ('Price') and resource ('an export of these traders') with the exact scope [from, to]. It also names the sibling it relates to (buy_export), so an agent can distinguish a free quote from the actual purchase without opening either schema.

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?

The line 'Charges nothing. orderPriceCents is what buy_export would charge from the balance.' clearly frames this as the pre-purchase pricing step versus the paid buy_export. It stops short of an explicit 'call this before buy_export' instruction, but the cost contrast makes the intended usage unambiguous.

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