rdap_lookup

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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is fully covered. The description adds only 'modern WHOIS replacement' framing and a list of return fields, which the output schema already conveys; it says nothing about rate limits, latency, or partial-data cases. With annotations and output schema doing the heavy lifting, a 3 is appropriate.

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?

Purpose is front-loaded, followed by return contents and then usage routing, in three tight sentences. The enumeration of return fields is slightly redundant with the existing output schema, costing a little efficiency but not readability.

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 an output schema, rich annotations, and 100% parameter coverage, the description only needs to establish purpose and routing, which it does fully. It is complete for an agent's needs, though it could note caching behavior rather than leaving that entirely to the force_refresh param.

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 domain, format, and force_refresh are already documented with examples and enum values. The description adds no parameter-level meaning beyond the schema, so the baseline 3 applies.

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 ('Fetch domain registration data via RDAP') and enumerates exactly what is returned: registrar, registrant contact, dates, EPP status codes, and domain age. It explicitly distinguishes itself from the sibling check_ns, so an agent can separate the two without opening either schema.

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 explicit when-to-use triggers ('who registered the domain, who the registrar is, or when the registration expires') and names the alternative check_ns along with its distinct purpose (DNS nameserver provider). Nothing about routing is left to inference.

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