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

Annotations declare readOnlyHint=false and openWorldHint=true, so the safety profile is partly covered structurally, yet the description never addresses what external data source is queried, whether calls are rate-limited or metered, or why a keyword lookup is flagged non-read-only. It does add useful value by enumerating the metric fields returned (search volume, trends, PPC bids, ranking difficulty), which annotations cannot express.

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 opening sentence is well front-loaded, but the remainder is a bloated trigger-phrase dump with heavy duplication ('keyword discovery' appears three times, 'keyword expansion', 'related keywords', 'PPC bid research' and 'keyword mining' each twice). This repetition adds no information and dilutes the signal.

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?

With 12 parameters, no output schema and a non-read-only profile, the description does meaningful work: it names the marketplaces and lists the metric categories returned, which substitutes for a missing output schema. It stops short of explaining how the many filter parameters combine or what the response shape looks like, but the essentials for calling it are present.

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 every one of the 12 parameters (sort, needCount, marketplace, word-count and volume filters) is already documented in the schema. The description adds no format hints, defaults or interaction notes beyond repeating the marketplace coverage already present in the marketplace field, 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?

States a specific verb and resource: it expands a seed keyword into a list of related keywords with search volume, trends, PPC bids and ranking difficulty, across 10 named Amazon marketplaces. The purpose is immediately clear. It does not, however, differentiate itself from close siblings such as nexscope_amazon_keyword_intelligence, nexscope_amazon_keyword_overview or nexscope_seo_keyword_expand, so an agent gets no signal on which to pick.

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 spends most of its length listing trigger phrases, which does convey when to activate the tool, but it provides no exclusions and never names an alternative sibling for overlapping needs. The implicit 'trigger when the user mentions X' framing is repeated rather than elaborated, so usage context is present but shallow.

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