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

The description discloses substantial non-obvious behavior: merging three first-party sources, seed-term expansion, sorting by match_count and volume, standard pagination, and specific volume_source semantics. This goes far beyond the readOnlyHint/destructiveHint annotations without contradicting them.

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?

The description is dense but front-loaded with the core purpose and data sources. The later detail about result fields and sorting is valuable for a tool with no output schema, though the sentence is long and could be lightly restructured without losing information.

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?

Since there is no output schema, the description usefully documents the returned term fields, volume semantics, ordering, and pagination. It leaves some optional parameter behaviors (weeks, min_match_count) and default values implicit, but the tool's fully-optional parameter set reduces the risk of incorrect invocation.

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?

With 50% schema coverage, the description compensates for key parameters: it explains asins as own-or-competitor reverse-ASIN input, terms as seeds expanded to top-clicked ASINs, and pagination for limit/offset. However, weeks and min_match_count are left without meaningful explanation in either schema or description.

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 clearly identifies a specific verb and resource: a reverse-ASIN/multi-input keyword lookup that returns every keyword phrase an ASIN is known for. It also distinguishes itself from keyword_opportunities, which is explicitly framed as the guided alternative.

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 gives concrete usage context: it handles both own and competitor ASINs, explains when each data source applies, and explicitly tells users to start with keyword_opportunities for guided workflows. It does not fully enumerate exclusions versus other keyword-related siblings like keyword_research or ppc_search_terms, but the guidance is clear enough for selection.

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