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

Annotations already declare readOnlyHint and openWorldHint, yet the description adds genuinely new behavior: reads public listing pages (no auth implied), a per-call price of $0.002 USDC via x402 on Base/Solana/Arc, and the fact that failed calls are not charged. The cost model is decisive information an agent can't get from annotations. Only the return format's cadence/pagination is unstated.

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 sentences, both dense with content and front-loaded with the resource and inputs before the pricing detail. The long field enumeration is slightly list-heavy and partially redundant given an output schema exists, but nothing is padded rhetoric.

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 enumerating return fields is redundant, but the description covers the essentials an agent needs: input format, per-listing scope, no catalog search, and the payment model. The main missing piece is disambiguation from the similarly named sibling tool.

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 single parameter is already documented with format and example. The description adds one useful clarification — that the ID is 'the number before .shtml in a listing URL' — which grounds the notion of a listing ID. Otherwise it repeats the 1-10 constraint already in the schema, so baseline 3 applies.

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+resource (listing tracker for Vestiaire Collective) with explicit scope: US site, USD, 1-10 listing IDs. The enumerations of returned fields make the tool's remit unambiguous. It does not, however, differentiate itself from the near-identically named sibling ecommerce_vestiairecollective, which an agent could easily confuse it with.

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?

'no catalog search' is an explicit when-not statement, and 'Reads each public listing page' implies this is per-listing lookup only. But there is no positive guidance on which situations call for this tracker versus other ecommerce tools, and nothing resolves the overlap with the similarly named sibling.

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