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

Given annotations already declare readOnly/openWorld/not-destructive, the description earns credit for adding real behavior: idempotency keyed by user+slug+UUID, owner-only free result retrieval with a concrete endpoint and sibling alternative, persistence in owner call history, and the important data-semantics warning that missing values are not zero. Deductions for 'Seven-day source-freshness rules apply only to dependent requests', which is unexplained jargon an agent cannot act on.

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?

Seven short sentences with no filler, and the purpose statement is front-loaded. However the body drifts into operational trivia (endpoint paths, freshness-rule jargon) that is denser than the missing core information about what metrics are produced.

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?

The description covers the async call lifecycle and null semantics, which suits a read-only annotated tool with no output schema. What it omits is the substance an agent most needs: which metrics are returned, and any constraint context for the three required parameters beyond what the schema enforces.

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?

Top-level schema description coverage is 0% (only the keywords item carries a note in the schema itself), and the description adds nothing about market, language, or keywords — 'explicit coverage for every input' is a claim, not an explanation. With low coverage the description was supposed to compensate by explaining what a keyword list means here or what market/language restrict, and it does not.

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 opening sentence names the resource ('keyword metrics') but supplies no verb and no scope beyond 'explicit coverage for every input', which is a marketing claim rather than a description of what is computed or returned. It does not distinguish this tool from the many closely related keyword siblings such as nexscope_seo_keyword_history, nexscope_seo_keyword_overview-adjacent tools, or nexscope_seo_keyword_intent, so an agent cannot tell which keyword tool to pick from this text alone.

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 guidance on when to use this tool versus the other keyword-metrics siblings. The only routing offered is about result retrieval ('GET .../calls/{callId} or nexscope_seo_call_result'), which is useful but addresses a follow-up step, not tool selection.

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