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

Annotations already declare read-only, idempotent, non-destructive and closed-world behavior, so the bar is lower. The description still adds real value by disclosing what the call returns ('same score, fixes and AI readiness as scan_page') and clarifying that url is only a resolution aid rather than a fetch target; it does not mention rate limits or the 900 KB ceiling (that lives in the 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?

Three sentences, each carrying distinct load: what to scan, what comes back, and the deployment-time use case. The primary differentiator (unpublished HTML) is front-loaded.

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 usefully summarizes the return payload by reference to scan_page, and it covers the input contract. It does not cover failure modes or size limits, but nothing critical for correct invocation is missing.

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 description coverage is 100%, so both parameters are already documented, including that url drives relative links and the canonical check. The description's 'Pass the full HTML document' and 'url is optional' largely restate that, adding little beyond the schema baseline.

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 and resource ('Scan raw HTML that is not published yet') and immediately distinguishes the input class from its sibling scan_page by naming unpublished sources such as local builds, templates and editor drafts.

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 a concrete usage context ('Use this in coding assistants to check SEO before deploying') and implicitly routes published pages to scan_page by referencing it as the equivalent tool. It never states an explicit exclusion or when-not-to-use, so it stops 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.