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

Annotations already declare readOnlyHint and openWorldHint, and the description adds substantial behavioral context beyond them: it reads public listing pages, does not provide catalog search, charges $0.002 per successful call via x402, and does not charge failed calls. This is materially useful for an agent deciding whether and how to invoke it.

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 description is dense but front-loaded and every sentence carries relevant information: scope, return fields, source behavior, constraints, and pricing. There is no filler.

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?

Given one required parameter, full schema coverage, annotations, and an output schema, the definition is complete enough for correct invocation. The description adds payment and source-page context while the output schema handles return shape.

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 documented in the schema, so the baseline is 3. The description adds useful detail by specifying that IDs are the number before .shtml in a listing URL and that up to 10 IDs are accepted, improving parameter interpretation beyond 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 and resource: a Vestiaire Collective listing tracker that returns detailed listing data for 1-10 listing IDs on the US site in USD. It is very clear, but it does not differentiate itself from the near-identically named sibling ecommerce_vestiaire_collective, leaving a potential ambiguity.

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?

It clearly indicates usage for known listing IDs and explicitly says 'no catalog search,' which tells the agent when not to use this tool. It does not name an alternative for catalog search, but the usage context is otherwise explicit.

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