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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is fully covered. The description's only added behavioral fact is the 30-day aggregation window, which is genuinely useful scope information, but it discloses nothing about rate limits, auth, or freshness beyond that.

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?

One front-loaded sentence that leads with the usage trigger before listing outputs; there is no filler. It is slightly dense with an embedded metric enumeration, but every clause carries information.

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?

An output schema exists, so return values need not be re-explained, and the single required parameter is fully documented in the schema. The description supplies enough intent-matching context for an agent to select the tool correctly; only the absence of explicit alternatives keeps it from a 5.

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?

There is a single parameter (site_id) with 100% schema description coverage, including a concrete format example ('bella-roma') and a pointer to list_sites. The description adds no parameter guidance, so the schema carries the full load and the baseline 3 applies.

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 states a concrete verb+resource ('how many visitors their site gets', 'how fast and well-built it is') and enumerates the returned metrics, so an agent can distinguish it from site-management siblings like get_site or list_sites. It stops short of explicitly naming an alternative, but the analytics framing is unambiguous.

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?

It gives an explicit trigger: 'Use when the user asks how many visitors their site gets or how fast and well-built it is.' That maps user intent to the tool cleanly. There is no when-not guidance or named alternative, so it falls short of a 5.

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