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

Annotations already declare readOnlyHint=true. The description adds valuable behavioral context beyond that: it explains that counting works without cookies or tracking scripts and that recent views may take about a minute to appear. This helps set expectations about privacy and data freshness.

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?

Two tightly written sentences, each earning its place. The first states the core outputs, and the second adds important behavioral caveats. No filler or repetition.

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?

Given the two parameters and no output schema, the description covers the main outputs, the time granularity, privacy behavior, and data freshness. It does not describe the exact response shape, but the listed metrics largely fill that gap for an agent deciding whether to call the tool.

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 schema documents the 'days' parameter fully, and the description clarifies that the resource is a 'site', giving some meaning to the otherwise undocumented 'site' parameter. However, with only 50% schema coverage, the description could do more to explain acceptable site identifiers or how the two parameters interact.

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 clearly identifies the tool's purpose with a specific resource ('site') and a concrete set of outputs: page views, unique visitors, top pages, referring sites, and serving location. It distinguishes this tool from all listed siblings, none of which provide visitor analytics.

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 establishes clear usage context: use this when you need visitor statistics for a site. It does not explicitly name alternatives or exclusions, but no sibling tool overlaps with this functionality, so the alternative guidance is not strictly necessary.

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