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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new context beyond that: it is a multi-source aggregation ('in one call') and it costs $0.02 per call, which matters for an agent deciding whether to call it repeatedly. It does not disclose behavior on partial failures (e.g., if WHOIS is unavailable) or latency/response size for a fan-out tool.

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?

Two sentences, front-loaded with the value proposition and the full content list, then the price. No filler, no restatement of the title, and every clause carries information an agent needs.

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 usefully doubles as a return-value outline by enumerating the report sections, and it discloses cost. For a one-parameter fan-out aggregator that could partially fail across sources, the missing piece is failure semantics, so it falls just short of complete.

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 required parameter with 100% schema coverage, and the schema already supplies the format example ('cloudflare.com'). The description adds nothing about the domain parameter, so the baseline 3 applies — the schema does all the 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 resource (a domain) and enumerates exactly what the report contains: DNS, registration, certificates, subdomains, email security grade, HTTP security headers grade, tech stack, website metadata, plus a summary. That enumeration distinguishes it cleanly from the single-facet siblings (dns_lookup, domain_whois, ssl_certificates, tech_stack, security_headers), making it obvious this is the aggregate tool.

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 phrase 'in one call' plus the $0.02 price implicitly signals that this is the bundled alternative to the free single-facet siblings, but the description never says so explicitly or names the conditions under which an agent should prefer dns_lookup or domain_whois instead. Usage must be inferred from the enumerated contents and cost hint rather than stated.

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