domain_check

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

With no annotations, the description carries the behavioral burden. It discloses the lookup order ('Tries RDAP first... falls back to WHOIS') and the return payload ('availability status and full registration data if registered'). It does not cover edge behavior such as timeouts, errors, or how method='both' changes behavior, but the core behavioral traits are transparent.

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 short sentences, each earning its place: purpose, algorithm, and return value. The most important information is front-loaded, and there is no filler or redundancy.

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?

The description gives a solid core outline but leaves gaps: no output schema exists, so the phrase 'availability status and full registration data' is vague about the actual response shape. It also does not mention error behavior, timeout implications, or how this relates to sibling tools like bulk_domain_check and whois_raw.

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 100%, so the schema already documents all three parameters. The description adds the rationale that RDAP is faster and structured, which is useful, but it does not meaningfully extend the parameter semantics beyond what the schema provides.

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 opens with a specific verb and resource: 'Check if a domain name is available for registration.' It also clarifies the tool's combined RDAP→WHOIS behavior and distinguishes it from raw lookup siblings by emphasizing availability status as the primary outcome.

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 use case is implied clearly: use this when you need an availability check. However, the description does not explicitly mention alternatives like whois_lookup, rdap_lookup, bulk_domain_check, or when the lower-level tools should be preferred instead.

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