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

Beyond the annotations, it discloses non-obvious behavior: robots.txt compliance, a 403 blocked_by_robots response that is explicitly not charged, same-host-only crawling, and a capped fan-out of 3 contact pages. These are exactly the operational traits an agent needs to predict cost and failure modes.

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 dense sentences with zero filler: output types first, then fetch scope, then robots handling. Every clause contributes information and nothing is repeated from the schema or annotations.

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 compensates by specifying what is returned (emails including mailto and [at] obfuscation, E.164 phones, social links, address hints, Swedish org numbers) and the network behavior. Nothing needed to call it correctly 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?

Only one parameter exists and schema description coverage is 100%, so the schema already carries the definition. The description adds a mild clarification ('usually the homepage'), but no format or syntax beyond the schema, meeting the baseline 3.

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 a specific verb (fetches) and a precisely scoped resource (public contact details on a website), enumerating the extracted types (emails, phone numbers, social links, address hints, org numbers). It is clearly distinguishable from siblings like site_audit or url_markdown, which do not target contact extraction.

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 defines the operating envelope: it fetches the given page plus up to 3 contact-like paths on the same host only, honouring robots.txt. An agent can infer when this tool is appropriate, but no sibling alternative is named or explicitly excluded.

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