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

Annotations already declare readOnly=true, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds useful behavioral content about what is returned (cross-shop spread, archive contradiction check), but says nothing about caching, freshness, or what happens when a shop lookup fails.

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 front-loaded sentence that packs the return payload into one readable clause chain. Slightly dense and rhetorical in the closing archive clause, but nothing is wasted.

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 one required param and no output schema, the description successfully conveys the shape of the response and the unusual archive-contradiction feature. Minor gaps remain about output structure and failure modes, but it is sufficient to invoke correctly.

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 with 100% schema description coverage, including an example path, so the schema carries the burden. The description adds no additional parameter semantics such as accepted formats, slug rules, or invalid-input behavior; 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 resource (one product) and enumerates exactly what is returned: every shop read, its price and stock, the spread, and an archive-capture cross-check. This clearly separates it from siblings like price_history, where_to_buy, and todays_deals.

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 explicit when-to-use guidance and no routing to or from alternatives, despite heavy overlap with price_history, where_to_buy, todays_deals, and fake_sales. The agent must infer selection from the description's content alone.

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