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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, and the description adds concrete operational traits beyond them: no JS rendering, 10-second overall budget, 2 MB HTML cap, max 20 links, and restricted public ports. It also sketches the return payload (schema 1, score, strengths, ranked fixes, facts), which matters because there is no output 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 tight sentences, with purpose front-loaded and constraints following in descending importance. No filler, no restatement of the tool name or title.

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 takes on the burden of describing returns and does so briefly; the size, time, link and port limits complete the picture. An agent has everything needed to decide whether calling it will succeed.

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?

The single required parameter is fully described in the schema ('Public http or https page URL'), so the baseline is 3. The description nonetheless adds real meaning by tying the URL to public ports 80/443 and an HTML (non-JS-rendered) page, narrowing what inputs will actually 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?

States a specific verb and resource ('Check one public HTML page') scoped by 'fixed SEO rules', so the agent knows exactly what analysis is performed. It does not name or differentiate against nearby siblings such as page_check or page_to_markdown, leaving that routing to inference.

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 applicability context: one page, public, HTML, no JavaScript rendering, ports 80/443 only. It never states when to prefer this over alternatives like page_check or find_data, but the operating envelope is unambiguous.

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