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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real context beyond that: the returned data shape (price, in-stock sizes, direct links) and the coverage trait ('long-tail coverage a feed-based catalogue does not have'), which signals it may return retailers a feed wouldn't. No pagination or rate-limit detail, but the added behavioral value is genuine.

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, front-loaded with the substantive content (retailers, price, sizes, link) and no filler. The trailing coverage claim is slightly promotional but still carries differentiating information, so it earns its place.

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 does the job of describing return contents, and it does so adequately. Annotations cover the read-only profile. The only real gap is the absence of any routing guidance versus cheapest_for_size, which affects the completeness of the overall definition.

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 schema itself already explains the one parameter ('product slug from search_sneakers'), including the sibling cross-reference. The description adds no syntax, format, or validation detail beyond that. Baseline 3 is appropriate when the schema carries the parameter burden.

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 a specific resource (tracked retailers carrying a given product) and enumerates what comes back: price, in-stock sizes, and a direct product-page link. That is concrete enough to tell it apart from list_brands and search_sneakers on its face. It stops short of explicitly contrasting with the closest sibling, cheapest_for_size, which also surfaces prices.

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?

There is no statement of when to reach for this tool over its alternatives. Nothing tells the agent to call it after search_sneakers to resolve a slug, nor when cheapest_for_size would be preferable over this broader price listing. Usage is only inferable from the return summary.

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