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

Annotations already declare this a safe read (readOnlyHint true, destructiveHint false, idempotentHint true), and the description still adds meaningful context: cookieless design, owner-only authorization, the 90-day retention window, and the privacy guarantee that no raw IP or full user agent is stored. The note that the accuracy field describes under-counting is real behavioral disclosure an agent needs when interpreting results.

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 tight sentences, front-loaded with what is returned before inputs are mentioned. Every clause carries information: no restating of the title, no filler.

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 carries the burden of describing the response and does so (per-day views, top paths, top referrers, crawler families) plus the accuracy caveat. Combined with full schema coverage and safety annotations, an agent has everything needed to invoke and interpret the call.

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 baseline is 3, but the description adds the 'maximum 90' range constraint that the schema omits and restates the from/to defaults in terms of the last 7 days, which clarifies how the two date params interact. The token parameter's fallback to Authorization: Bearer is covered in the schema rather than the description.

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 (Returns) and resource (cookieless analytics counts for a slug) and enumerates the returned dimensions: views per UTC day, top paths, top referrer hosts, and AI crawler counts by user-agent family. No sibling tool returns analytics, so the agent can disambiguate this from list_sites/get_site purely from the description.

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?

Gives clear operating context: 'owner-only' establishes the prerequisite, defaults are spelled out (last 7 days), and a hard cap (maximum 90 days) is stated. It doesn't name any when-not condition or alternative tool, but no sibling provides comparable analytics, so there is little to exclude.

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