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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open-world), yet the description adds genuinely new behavioral context: every fact carries a tone label (obychno/vnimanie) plus an explanation, and the server explicitly does not issue a verdict or scan for malware. Those caveats shape how an agent should interpret and relay the output. It stops short of describing completeness or failure behavior for unresolvable domains.

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?

It runs to three sentences and is front-loaded with the purpose, then the output shape, then the limitation. Every sentence carries information, though the mixed-script typo in 'тон obychno' slightly hurts readability of the return-value explanation.

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 must convey what comes back, and it does: a set of labeled facts, each with a tone and an explanation. Combined with the explicit scope limits, an agent has enough to call it and interpret results, though it says nothing about behavior on unresolvable or malformed domains.

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?

There is a single parameter with 100% schema description coverage, including example input formats (shop-example.ru or https://www.shop.ru/), so the schema carries the load. The description adds nothing about the domain argument itself, which matches the baseline 3 for a fully documented single parameter.

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 resource (facts about a site, by domain) and enumerates exactly which facts are returned: domain age, registrar, owner privacy, HTTPS certificate, hosting network, SPF/DMARC. That is far more than a restatement of the name. What it lacks is differentiation from close siblings such as whois_domain, dns_records and check_domain, which visibly overlap with parts of this output.

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?

The intended context is implied ('for evaluating an unfamiliar site'), along with an explicit boundary on what the result should not be used for (no final fraud/honesty conclusion). However, no alternative tool is named and no condition for choosing this over whois_domain or dns_records is given, so the agent must infer sibling routing on its own.

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