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

The description adds substantial behavior beyond the annotations: three parallel HTTPS fetches, 64 KB caps per fetch, and the full set of status responses including 'not_applicable', 'timeout', and 'error'. It also advises how to interpret those statuses, which is valuable 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?

The description is front-loaded with purpose and use case, then packs behavior and response semantics into a compact set of sentences. The status payload examples earn their place because they define the tool's contract.

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 one simple parameter, no output schema, and only readOnly/openWorld annotations, the description explains the request behavior and response statuses thoroughly. The only minor gap is that the shape of the 'data' field for the successful case is not detailed, though it is roughly inferable from the listed surface components.

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%, and the schema already documents the 'domain' parameter thoroughly, including rejected forms like IPs, ports, paths, and protocols. The description reinforces that the domain is the subject of the summary but adds no new parameter-level meaning, so the baseline of 3 is appropriate.

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 specific verb and resource: 'Summarise a domain's public web surface' followed by explicit components (robots.txt, sitemap.xml, home page meta tags). It clearly distinguishes this from sibling recon tools by focusing on SEO/link-preview surface rather than DNS, headers, or TLS.

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 clear usage context: 'Use for a quick SEO or link-preview review.' It does not explicitly name alternatives or state when not to use the tool, so it falls short of the top score, but the intended scenario is unambiguous.

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