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

Annotations only say this is a safe, idempotent, open-world read. The description adds the material facts an agent cannot infer: the call is billed against the agency's own DataForSEO account, the response reports the per-call cost and remaining monthly quota, and an identical query within the same day is served from cache at zero cost. Cost and rate/quota behavior are exactly the traits annotations do not cover.

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 output fields and batch limit lead, followed by the use case, then cost and caching — a sensible front-loaded order. Four sentences with no filler, though the closing cache sentence is run-on and reads slightly informally, keeping it just under a 5.

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?

There is no output schema, and the description compensates by naming the returned metrics and by explaining that the response also carries cost and quota figures. Combined with the cost/caching caveats and the documented parameters, an agent has everything needed to call this correctly and understand the consequence of calling it.

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% and all three parameters (keywords, language, location) are documented with defaults and format examples in the schema itself. The description only restates the 100-keyword cap and the single-market constraint, adding no syntax or format guidance beyond that, 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?

The first sentence names the exact resource (keyword metrics) and enumerates the returned fields — monthly search volume, CPC, advertiser competition, difficulty 0-100 — plus the batch limit and the 'one market' scope. That is enough for an agent to tell it apart from sibling tools such as seo__ranked_keywords or seo__related_keywords without opening any 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?

"Use it to check that a page or keyword has search demand before writing for it" gives a concrete trigger, and the caching/cost sentence implicitly tells the agent not to re-issue the same query repeatedly. It stops short of naming an alternative tool or stating when not to use it, so it stays at a clear-context-but-no-exclusions 4.

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