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

Annotations already declare readOnly, non-destructive, idempotent, and openWorld. The description adds useful behavioral details beyond that: deduplication, the 6-entry limit, and the single-element array for a bare IP. It does not address error cases or rate limits, but the annotation bar lowers the requirement.

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 tight sentences, front-loaded with the main purpose and limits, then a concise return-format note. No filler or repetition of schema content.

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 one-parameter read-only tool with strong annotations and an output description embedded, this is largely complete. It lacks explicit guidance on failure modes (e.g., unresolved domains) or rate limits, but overall it gives an agent enough to invoke and interpret the tool correctly.

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 schema already describes host as a domain or IP. The description adds extra semantics by explaining the return shape differs for bare IPs ('single-element array'), which gives the agent a clearer expectation of behavior tied to the parameter.

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 verb and resource ('Resolve a domain to all its A and AAAA records') and adds concrete scope details: deduplication, a 6-record cap, and geolocation. This clearly distinguishes it from sibling tools like ip_lookup or ip_self, which likely serve different lookup purposes.

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 conveys a clear context for use: resolving domains to IP addresses with geolocation, and also notes behavior for bare IPs. However, it does not explicitly name sibling tools or state when NOT to use this tool, so it falls short of the 5-level standard.

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