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

With no annotations supplied, the description carries the full behavioral burden and does so thoroughly. It discloses returned data categories, absence of registrant personal data, RDAP availability limitations, charging rules, and error behaviors including NXDOMAIN, upstream failure, and bad input.

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?

The description is front-loaded with the core purpose and packs dense but relevant operational information into one paragraph. It is longer than typical, but most details earn their place given the absence of annotations and an output 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?

For a tool with no annotations and no output schema, the description is highly complete. It explains what data comes back, which TLDs may lack RDAP data, how errors are treated, and how charging works, leaving little an agent would need to infer before calling it.

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 100% and the single domain parameter is already documented in the schema with examples and normalization notes. The description adds no further parameter meaning beyond what the schema provides, so the baseline of 3 is appropriate.

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 states a specific resource and action: domain lookup returning DNS records and RDAP registration data. It enumerates record types and registration fields clearly. It does not distinguish this tool from the sibling domain_auth_check or domain_lookup_bulk, so it falls short of a 5.

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 description never says when to use this tool instead of domain_auth_check or domain_lookup_bulk. It provides useful operational details such as TLD limitations and charging conditions, but no explicit selection guidance or exclusions.

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