Hivex: .si names, DNS and WHOIS

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 covered. The description adds genuinely new behavior: a DNS lookup performed at call time (explaining the openWorld hint) and the fact that the result is a hivex.si page rather than a definitive registry verdict. It does not mention caching or rate limits on the live lookup.

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 sentences, front-loaded with the lookup and its possible outcomes; almost every clause earns its place. The second sentence is slightly dense and mixes return description with usage context, which is the only structural weakness.

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?

An output schema exists, so return-value documentation is not required, and the description nonetheless flags the key nuance that the response is a hivex.si page rather than the authoritative registry answer. For a single-parameter read tool this is nearly complete; only explicit when-to-use guidance versus find_names is absent.

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?

There is one parameter and schema description coverage is 100%, with the schema already giving the 'with or without .si' example, so the description adds no syntax detail beyond what is structured. Baseline 3 applies when the schema carries the parameter semantics.

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 names a specific verb ('look up') and resource ('one .si domain name') and enumerates the three statuses it can return (free/likely free, for sale, registered) plus a live DNS lookup. The word 'one' implicitly contrasts with the plural sibling find_names, though it never names that sibling outright.

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?

Usage is only implied: the second sentence situates the tool as the pre-registration check whose hivex.si page hosts the final live registry check. There is no explicit statement of when to prefer this over find_names, nor any exclusion or prerequisite (e.g. rate limits on the live DNS lookup).

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

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

Annotations already establish read-only, idempotent, open-world, non-destructive behavior, so the bar is lower. The description nonetheless adds real context: queries are live, they go through Cloudflare's public resolver, and responses include TTLs plus an explanatory page.

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 dense sentences, front-loaded with what the tool does before enumerating types and return details. Informative without padding, though the type enumeration is slightly list-heavy.

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 present the description need not explain return values, and it covers the resolver, live behavior, record types, and reverse lookups. Mildly thin on pagination/limits for a forward lookup that can return many records, but otherwise complete.

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% and the enum enumerates the types, so the schema carries the load. The description reaffirms record types and the reverse-DNS/PTR case but adds no syntax or format detail beyond the schema.

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+resource ('Look up the DNS records of any domain or hostname') and adds scope (live, via Cloudflare's public resolver, including reverse PTR). It does not explicitly distinguish itself from whois_lookup or check_name, so it stops short of the 5 given the sibling set.

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?

Usage is implied rather than stated: the reader infers this is the tool for DNS queries and that PTR is used for IPs. There is no explicit when-to-use/when-not or routing to whois_lookup for registration data, so it is minimum-viable guidance.

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

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

Annotations already declare the safe read-only, idempotent, closed-world profile, so the bar is lower. The description adds real behavioral context beyond them: the results come from a Hivex index (implying staleness/coverage limits), are capped at 25, and each carries a hivex.si page link. It does not note the default status of 'any' meaning results may not be free, which is a minor gap.

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 dense sentences with no filler, front-loading what is searched before the filter options. The option lists are slightly crammed together but every clause carries information.

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 present, return-value detail is not required, yet the description still notes the 25-result cap and the accompanying page URL. For an 8-parameter, zero-required search tool it is sufficient to call correctly; the main omission is any guidance on the unchecked defaults (limit=10, status='any').

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 only 38%, so the description carries weight – and it does, restating and expanding the fragment match modes (contains/starts with/ends with/exact), the length bound, the minimum score, and the three sort orders. It leaves 'limit' and the default values undocumented, which keeps it short of a 5.

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 gives a specific verb and resource: 'Search Hivex's index of .si domain names that are free to register,' which is unambiguous. It does not, however, differentiate itself from the only sibling, check_name, so an agent cannot tell from the description alone when to search the index versus checking one 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?

Usage is implied by the enumerated capabilities (filter by fragment with contains/starts/ends/exact, length, score; sort by best/newest/shortest), which tells an agent what the tool is useful for. There is no explicit 'when to use this vs check_name' guidance and no statement of prerequisites or exclusions.

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

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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so the safety profile is covered. The description adds genuinely useful context on top: a live registry/RDAP source, an explicit privacy guarantee ('Personal details of the holder are never returned'), and an outbound link to the explained record.

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 front-loaded sentences with no filler; the capability and the privacy caveat come first. The trailing 'Links to the explained record on hivex.si' reads slightly promotional and is partly redundant given an output schema exists, which keeps it from a 5.

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?

An output schema exists, so return structure need not be documented, and the description still enumerates the salient fields and adds a privacy guarantee. For a single-parameter read-only lookup with full annotation coverage, an agent has everything it needs to call it 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?

There is one required parameter with 100% schema description coverage, including the note that a hostname is reduced to its domain. The description adds nothing to the parameter beyond 'any domain', so the schema carries the load and the baseline of 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 precise verb and resource ('look up the registration record of any domain') plus the data source ('live from its registry's RDAP'), which cleanly separates it from a DNS-resolution sibling. It does not name check_name, dns_lookup or find_names, so sibling differentiation remains implicit rather than explicit.

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 stated outputs (registration status, registrar, dates, status codes, name servers) imply when to reach for it, but there is no explicit when-not-would-be-better guidance and no alternative tool named. Usage is inferable, not spelled out.

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