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

Annotations already declare readOnlyHint, idempotentHint and non-destructive behaviour, so the safety profile is covered. The description adds genuinely useful behavioural context beyond them: the fixed 30-day aggregation window and the specific metric families returned. It does not discuss data freshness, rate limits, or permission requirements, so it is not fully complete.

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 sentence, front-loaded with the usage trigger and followed by the returned metric inventory. No filler, no repetition of the title, and every clause carries information an agent needs.

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 and annotations cover safety, so the description need only frame intent and content, which it does. The 30-day window and metric list give enough to decide to call it. Minor gaps remain around result freshness and any limits on historical data available.

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?

With a single required parameter at 100% schema description coverage, the schema already explains site_id with a concrete URL example and a pointer to list_sites. The description adds no further meaning about that parameter. Baseline 3 is appropriate when the schema does all the work.

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 names the resource and scope concretely: views per day over 30 days, top pages, referring websites, and phone scores for performance, accessibility, best practices and SEO. It is clearly distinguishable from sibling tools like get_site or list_sites by the metrics it returns. It stops short of explicitly naming a contrasting sibling, so a 4 rather than a 5.

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 opens with an explicit trigger condition: 'Use when the user asks how many visitors their site gets or how fast and well-built it is.' That maps user intent to this tool well. There is no when-not guidance or named alternative for adjacent questions (e.g. site metadata), which keeps it below 5.

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