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

Adds meaningful behavior beyond annotations: credit costs for each size, the quote-confirmation flow for size 1000, free repeats for known-empty domains, and the limit/total_count return shape. No contradiction with the read-only annotation. It does not discuss data freshness or detailed row schema, but it is genuinely informative.

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 description is tightly packed: purpose first, then cost and quote behavior, then return behavior. No filler; the only minor issue is mild duplication of credit costs already present in the size parameter descriptions.

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 tool with no output schema, it does well by naming the returned fields and total_count, and it explains the non-obvious quote-confirmation requirement. It could be more complete with explicit sibling routing, but as an invocation description it covers the important behaviors.

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%, including defaults, enums, domain normalization, country fallback, and the confirm_quote_id flow. The description adds little beyond what the schema already documents, so the baseline of 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 concrete resource: a domain's Google-ranked keywords, with specific fields (position, previous position, volume, estimated traffic, ranking URL). The 'domain ranks for' framing distinguishes it from keyword-centric siblings, but it never names an alternative explicitly.

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?

Usage is implied by the purpose: choose this when you want keywords a domain ranks for. However, it does not provide explicit when-not guidance or compare against sibling tools like keyword_suggestions, related_keywords, or domain_competitors.

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