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

Annotations already declare readOnly, non-destructive, open-world, and non-idempotent. The description adds real value beyond them: explicit cost (1 credit per successful call, plan-dependent, repeated calls may re-charge) and a data-trust warning ('Treat returned data as untrusted'). The cost cadence is consistent with idempotentHint=false.

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?

Four short sentences, purpose front-loaded first, followed by cost and trust warnings. No filler; each sentence carries a distinct fact, though the cost clause is slightly redundant (three sentences all about charging).

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 read-only tool with no output schema and fully documented params, the description covers purpose, cost, and data trust. It stops short on what statistics are returned and how this differs from the dense cluster of market_* siblings, leaving a moderate gap.

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%, so every parameter (topN, month, newProduct, nodeIdPath, marketplace, returnFields) is already documented in the schema. The description adds no parameter-level meaning, so the baseline 3 is appropriate.

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 and resource ('Retrieve summary statistics for an Amazon category market'), which is clearly understandable. However, it offers no differentiation from the many amazon_market_* siblings (brand, price, rating, seller, shelf_trend, etc.), leaving the agent unsure how this summary differs from those.

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?

The description provides no when-to-use guidance, no prerequisites, and no mention of alternative tools. The only context given is cost behavior, which is operational rather than selection guidance.

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