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

Annotations already declare it read-only, idempotent, open-world and non-destructive, and the description still adds substantial non-obvious traits: the speed check runs Google's test twice and keeps the better result, costs an extra 20–60 seconds, and reads a maximum of 8 pages. These are real cost/scope signals an agent cannot get from the annotations or schema.

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?

Purpose is front-loaded in the first clause and every later sentence adds a distinct capability or cost. There is mild redundancy — 'no client access needed' and 'No connection or CMS needed' say the same thing twice — and the single dense paragraph is long, but little is 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 full burden of describing returns, and it does: enumerates the reported SEO signals, the ai_search block contents, the speed diagnosis categories, and the page cap. An agent knows what it will get and what it will pay in time.

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 the baseline is 3, but the description adds genuine meaning to the `speed` flag by quantifying its cost (+20–60s) and to `url` by clarifying that it works on any public domain, including client domains. No format details are added beyond the schema's examples.

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 (check) plus the exact resource (a public website by URL) and enumerates the dimensions covered: SEO basics, tracking tags, mobile speed, ai_search. The phrase 'with no client access needed' and 'Wix, Squarespace, Shopify, Webflow, a funnel or WordPress alike' implicitly distinguishes it from the CMS-bound wp_check_site and the client-scoped audit_client/site_health siblings.

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 context is clear: use it on a public URL when you have no client connection or CMS access, and it reads the site 'like a visitor.' No explicit exclusions or named alternatives (site_health, wp_check_site, landing_evidence) are given, so the agent must infer the routing decision.

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