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

Annotations already cover the safety profile (readOnly, idempotent, openWorld), and the description adds value beyond them: per-section failure isolation ('comes back as an object with an `error` field and the rest is unaffected') and the latency tradeoff of wait=true ('up to about 20 s'). It does not mention rate limits, auth requirements, or cost, which keeps it from a 5.

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, front-loaded with scope, then usage, then the two behavioral caveats. Every sentence adds decision-relevant information and nothing is repeated from the annotations or schema.

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?

An output schema exists, so return-value documentation is not required, and the description still adds the per-section error-object shape. For a read-only open-world aggregator with three params it is nearly complete; the only real gap is the unexplained subdomain_limit and any coverage/truncation limits on the sections.

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 0%, so the description must carry parameter meaning. It explains wait=true well (wait for every subdomain source vs the fast first result, ~20 s), but subdomain_limit is never mentioned and domain is left to the schema. Only the most non-obvious of three parameters is covered, so partial compensation.

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 ('Full report on a domain') and enumerates exactly the five data sections (WHOIS/RDAP, DNS, SSL, subdomains, email auth) that map to the five sibling tools, so an agent immediately sees this as the aggregator rather than a single-section lookup. The phrase 'in one call' makes the contrast with the granular siblings explicit.

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 concrete when-to-use cases ('triage a suspicious domain or profile a company's domain'), which is real routing guidance. It stops short of stating when NOT to use it (e.g., when you only need one section and should call dns_records or whois_lookup instead), so the alternative-selection condition is left implicit.

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