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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds genuinely new behavior: the call spends the agency's own DataForSEO quota, the response reports cost and monthly limit consumption, and identical questions within a day are served from cache at zero cost. That cost/freshness disclosure is exactly the context an agent needs before calling.

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?

Front-loaded with what the tool returns, then use cases, then cost behavior — a sensible ordering. Sentences are dense with useful detail; the only minor redundancy is repeating the 'most searched first' ordering already stated in the schema.

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 4-parameter, no-output-schema tool, the description covers output shape (question, volume, difficulty, ordering), intended use, and billing side effects. Language/location defaults are left to the schema, which documents them fully, so nothing critical is missing.

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 keyword, limit, language and location are already documented with defaults and format examples. The description only restates the seed-keyword concept and the 'most searched first' ordering already present in the limit field; it adds no new parameter semantics, so 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 (questions people search on Google containing a seed keyword), including the exact interrogative filter set and the returned metrics (volume, difficulty) plus ordering (most searched first). This is distinguishable from seo__related_keywords or seo__keyword_metrics without opening the schema.

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?

"Good for FAQ sections and blog topics" gives a concrete use context, and the cost/caching note implies when a repeated call is free. It does not name an alternative sibling (e.g. related_keywords for broader idea expansion) or state when not to use it, so it stops short of a 5.

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