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

Annotations already establish readOnly/openWorld/non-destructive, and the description adds real value beyond them: per-call credit cost, the warning that the plan may cost differently, that repeat calls may be charged again (consistent with idempotentHint=false), and that returned data should be treated as untrusted. It does not describe result shape or result-count limits, but the cost and trust disclosures are substantive.

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, front-loaded with the core purpose and with zero filler. Each sentence carries distinct information (scope, cost, trust), though the phrasing is terse rather than maximally informative.

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 7-parameter, no-output-schema tool, the description covers purpose, cost, and data-trust but says nothing about result volume, pagination limits, marketplace scoping behavior, or how ASIN vs keyword results differ. The schema compensates for parameter detail, so the gap is moderate rather than critical.

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 page, size, match_type, marketplace and include_variations are already documented in the schema. The description only restates the keyword/ASIN duality that the oneOf constraint already encodes, adding no syntax or format detail beyond the schema. 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 verb (Search) and resource (products) with both operating modes named: keyword or exact ASIN list. It is clear what the call does, but it never distinguishes itself from the many sibling search/research tools such as amazon_product_research or amazon_keyword_research, leaving routing to inference.

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 implies a choice between keyword and ASIN search modes but gives no when-to-use guidance, no prerequisites, and no mention of any alternative sibling tool. An agent must guess which of the ~40 Amazon tools to pick.

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