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

Annotations already establish it as a read-only, open-world, non-destructive call, so the bar is lower. The description adds genuinely new behavioral context beyond that: per-call credit cost, the fact that repeated calls may charge again, and a prompt-injection caution to treat returned data as untrusted.

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?

Three short sentences, no filler, with the core purpose front-loaded before the cost and safety notes. Efficient and easy to scan, though the cost sentence is somewhat boilerplate-heavy.

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?

Cost and trust caveats are covered, which is more than most siblings offer. With no output schema, though, the description never hints at what the aggregate statistics contain or how they differ from the closely-named sibling tools, leaving a gap for a data-retrieval tool with four parameters.

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 the schema already documents asin, month, marketplace, and returnFields including the yyyyMM format and enum values. The description adds no parameter-level meaning beyond the schema, which is the expected baseline at full coverage.

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 states a clear verb+resource: 'Retrieve aggregate traffic keyword statistics for an ASIN.' An agent knows it is an aggregate keyword-traffic lookup keyed on an ASIN. It does not, however, distinguish itself from the near-identical sibling amazon_traffic_keyword, leaving the boundary ambiguous.

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, no prerequisites, and no mention of when to prefer a sibling such as amazon_traffic_keyword or amazon_traffic_listing_stat. The closest thing to guidance is the cost warning, which is about billing, not selection.

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