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

Even with readOnlyHint=true already covering the safety profile, the description adds substantial behavioral details: cost tiers, credit charging even for empty results, the quote-and-confirm flow for expensive calls, and the return format sorted by volume. This goes well beyond the annotations and is consistent with idempotentHint=false.

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?

Three compact sentences cover scope, cost, quote behavior, and return shape with no filler. The most important differentiator ('many keywords in one call') is front-loaded.

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, the description still explains return behavior ('one row per keyword found, sorted by volume, up to limit rows'). All four params are documented, costs are explicit, and the quote confirmation flow is clarified. An agent has everything needed to call and interpret the result.

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 coverage is 100%, so the baseline is 3; the description adds meaningful semantics by explaining how keyword count maps to cost and that the limit affects returned rows but not cost. It also indirectly explains confirm_quote_id through the quote-confirmation behavior.

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 specific resource ('many keywords') and the exact metrics returned ('Volume, CPC, KD, competition and intent'), with an explicit batch size range. It is clearly differentiated from the sibling keyword_overview by the 'many keywords in one call' phrasing.

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?

The description makes it clear this is the batch variant by saying 'for many keywords in one call (1-700 keywords)', which signals when to reach for it. It does not explicitly name keyword_overview or other alternatives, but the context is clear enough and the cost/quote flow gives additional situational guidance.

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