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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and openWorldHint=false, so the safety profile is covered. The description contributes semantic framing (what constitutes a 'fake' discount) but says nothing about pagination, result ordering, or how many matches typically come back.

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?

One tight sentence with no filler, front-loading the anomaly definition. It is efficient, though the abstraction level means the reader still has to infer that the output is a product list.

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?

For a zero-required-parameter read-only tool with annotations and full schema coverage, the description is adequate but thin: no output shape (no output schema exists) and no routing against the three sibling tools that return overlapping deal/price data.

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 description coverage is 100%, so brand, limit and vehicle are fully documented in the schema, including the default/max for limit and the allowed vehicle values. The description adds no parameter meaning beyond that, so the 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?

The description defines a precise domain concept: products with illusory discounts (cross-shop price gaps or phantom crossed-out prices). An agent can tell what class of data this returns, though unlike a sibling-aware definition it never names or contrasts with todays_deals or price_history, which occupy similar territory.

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 when-to-use guidance at all. With siblings like todays_deals and price_history, an agent has no stated condition for preferring fake_sales over a plain deals listing or a price-history lookup.

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