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

The description does add real behavior beyond the thin annotations: idempotency keyed on user/slug/UUID, an async call-result retrieval path with an owner-only history, a seven-day freshness rule for dependent requests, and a 'missing values are not zero' null-semantics warning. However, all of it is stated in dense, unexplained jargon ('explicit coverage for every input', 'dependent requests'), so the agent has to guess at the operational meaning.

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 text is short but poorly front-loaded: the opening sentence is the least informative one, and the remaining sentences are an unordered list of caveats (idempotency, retrieval URL, retention, freshness, nulls, examples disclaimer). Several phrases add words without adding meaning.

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 no output schema and no parameter documentation, the description is the only source of truth, yet it never describes what a 'keyword metric' contains or how results are shaped. It covers the async/retrieval mechanics reasonably but leaves the core payload behavior unexplained.

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 0% and all three parameters are required, so the description should be carrying this load — instead it says nothing about market, language, or keywords beyond the meaningless phrase 'explicit coverage for every input.' Only the self-documenting US/en enums give an agent any grounding.

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 names the resource (keyword metrics) but never says which metrics are returned or what operation is performed, and it never distinguishes this tool from the many keyword-named siblings (keyword_history, keyword_interest_history, keyword_categories, keyword_expand). An agent knows the general domain but not the specific capability.

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 a routing hint for retrieval (GET .../calls/{callId} or nexscope_seo_call_result), which implies this tool kicks off a job rather than returning data directly. But there is no statement of when to choose this over the numerous alternative keyword tools, and no preconditions, exclusions, or cost/latency guidance.

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