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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world, so safety is covered. The description adds genuine behavioral context beyond that: the exact breadth of returned data (current price, stock, cheapest shop, 90-day low/high/usual/last change, verdict, specs, alternatives), which is valuable since there is no output schema.

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?

A single dense sentence with the payload list front-loaded and the usage/input guidance trailing. Every clause earns its place, though the enumeration is long enough that it reads more like a feature dump than a crisp summary.

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 must convey return contents, and it does so thoroughly (prices, stock, cheapest shop, 90-day history metrics, verdict, specs, alternatives). An agent knows what it will get and what input forms are valid.

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?

Only one parameter and schema description coverage is 100%, so the schema already documents it fully. The description's 'Accepts the product url or slug... or a product name' restates the schema's 'Product page url, slug, or name' rather than adding format, resolution-order, or ambiguity-handling detail. Baseline 3.

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 ('Everything about one product') and enumerates the exact payload: per-shop price/stock, cheapest shop, 90-day history, verdict, specs, alternatives. It is clearly distinguishable from search_products (which feeds it) and from similar_products/price_drops.

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?

Gives an explicit when-to-use directive ('Use before recommending a purchase') and names the upstream source of its identifier ('the product url or slug from search_products'). It does not say when to prefer sibling tools like price_drops or similar_products instead, so no exclusion guidance.

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