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

Annotations already declare readOnly/openWorld/idempotent, and the description adds real behavioral detail: data source, availability heuristic, phishing/risk flag for domains under 30 days, and per-call cost. This is exactly the kind of added context the dimension is looking for, with no contradiction.

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?

Every sentence earns its place: output fields, data source, availability logic, risk heuristic, and pricing. The core answer is front-loaded and no structural information from the schema or annotations is repeated.

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?

There is no output schema, but the description lists the key returned data points and the availability verdict, plus important interpretation caveats and cost. For a single-parameter, read-only lookup, an agent has enough to call it correctly and interpret its result.

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 0% and the description does not explicitly specify domain format (e.g., no protocol, no path). However, with a single required string parameter named 'domain', the intended input is fairly self-evident from the schema and the surrounding domain-focused prose, so it barely compensates.

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 clear verb-resource promise: report who registered a domain and when, with registrar, dates, age, expiry, status locks, nameservers, or availability. This distinguishes it from DNS/network siblings and goes well beyond merely restating the tool name.

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?

Provides concrete context: RDAP is the registries' official WHOIS successor, availability is inferred when no RDAP record and no DNS exist, and young domains are flagged as risky. It does not explicitly name alternative tools or exclusion conditions, so it stops short of a 5.

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