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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed-world scope, so the safety profile is fully covered. The description adds genuinely new context beyond the annotations: the specific axes of the breakdown and the fact that under-sampled strata are surfaced, which tells the agent what information it will get back.

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?

A single front-loaded sentence naming the subject first, then the reported dimensions. Dense but every clause carries content; the list of breakdown axes could arguably be trimmed but each one communicates real scope.

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 parameters, no output schema, and a low-complexity read operation, the description must carry the return-content burden and largely does, describing both the headline counts and the stratification. Minor gap: no indication of whether results are cached, filtered, or paginated, though for an overview tool this is a small omission.

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?

The tool takes zero parameters, so the baseline is 4. There is no parameter-level meaning to add, and the description correctly spends its words on output content instead.

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 resource (CrawlCheck's public dataset coverage) and enumerates exactly what is reported: distinct domain counts plus breakdowns by platform, rendering, size, language, and kind. The purpose is unambiguous, though it never explicitly distinguishes itself from the similarly-scoped sibling `public_counts`.

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 only implied: an agent can infer this is a dataset-level overview rather than a per-domain lookup, but there is no when-to-use statement, no prerequisites, and no routing to an alternative such as `public_counts` or `resolve_domain`. Nothing is misleading, but nothing is spelled out either.

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