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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so the safety profile is covered. The description adds genuinely new behavioral context: cost per view, that backlinks refresh incurs a paid fetch, and that non-refresh calls return a cached snapshot. Return format is left to the output schema.

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 purpose and view enumeration, then cost, then refresh semantics, then related tools. Dense but every sentence carries information; minor redundancy in re-listing the view options already in the enum.

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 read-only analytics tool with a full output schema and 100% schema coverage, the description supplies the missing decision-relevant layers: view selection, paid refresh behavior, and cost. Nothing needed to call it correctly is absent.

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 baseline is 3, and the description adds value beyond it by mapping cost to each view and clarifying refresh's paid-vs-snapshot trade-off. It also implicitly ties the url parameter to the page_keywords view. It stops short of detailing languageCode/locationCode defaults beyond the schema.

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 ('Looks up any domain') and enumerates the four distinct views it can return. The parenthetical 'yours or a competitor's' clarifies scope, and the 'Related' line points at sibling territory so an agent can separate this from research_keywords/get_rankings.

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?

Explains the key decision point for the refresh parameter (paid fresh fetch vs latest snapshot) and surfaces per-view costs, which materially guide invocation. However, it only lists related tools without stating when an agent should prefer research_keywords or get_rankings over this one, so no explicit exclusion guidance.

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