RDAP API

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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is clear from structured data. The description adds value by naming the underlying source ('normalized RDAP data') and the returned fields, but says nothing about rate limits, auth, or failure behavior for an open-world 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?

A single front-loaded sentence that names the action, the source, and the returned fields with no wasted words.

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, non-destructive read tool with no output schema, the description usefully enumerates the returned data (holder, country, status, registration dates). Only the absence of any caveats for open-world lookups keeps it from being fully 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 sole parameter's format ("15169" or "AS15169") is documented in the schema, so the description adds no parameter meaning beyond what is already structured. This is the expected baseline when the schema does the work.

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 (look up) and resource (autonomous system number) and enumerates the RDAP fields returned, making the purpose concrete. It does not explicitly distinguish itself from the closely related ip-lookup sibling, so it stops 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?

Usage is only implied by the name and description: use it when you have an ASN and want registry data. There is no guidance on when to prefer ip-lookup or domain-lookup, nor any prerequisites, though for a single-parameter read tool the intent is reasonably inferable.

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/openWorld/non-destructive, so the description's added value is the plan gating and the per-domain quota accounting — genuine behavioral facts not in structured data. It stops short of describing batch failure semantics (e.g. whether one bad domain fails the whole call), but covers the commercially important behavior well.

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, zero filler, with the core action front-loaded and the plan/quota caveat second. Every clause earns its place.

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 three-parameter read tool with no output schema, the description plus rich schema descriptions and annotations cover calling correctly. The notable remaining gap is return/error shape for partial batch failures, which 'normalized RDAP registration data' only hints at.

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 whois, follow, and domains are already fully documented in the schema, including the 1-10 limit and IDN handling. The description adds nothing parameter-specific, making the baseline 3 the correct score.

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 ('Look up normalized RDAP registration data') plus the batching scope ('several domain names in one pooled call'), which is exactly what separates it from the sibling domain-lookup. An agent can pick between single and bulk 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?

Gives real eligibility and cost context (requires Pro or Business plan; each domain counts against quota), which is useful pre-call guidance. However, it never states when to prefer this over domain-lookup for a single name, or when-not to batch, so alternative selection 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.

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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description usefully adds the shape of the returned data, but says nothing about the WHOIS/port-43 fallback or the latency of the follow behavior, both of which are notable traits disclosed only in the parameter descriptions.

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?

A single front-loaded sentence naming the operation, the data type, the key input, and the returned fields, with no filler.

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 no output schema, the description compensates by enumerating the principal return fields, and the schema covers the two behavioral flags. It lacks any routing guidance among the sibling lookup tools, which is the only material gap.

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 explains domain, whois and follow semantics in detail. The description adds no parameter-level meaning beyond that, which is the correct baseline when the schema does the heavy lifting.

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 ("Look up") and resource (normalized RDAP registration data for a domain name) and enumerates the returned fields (registrar, status, dates, nameservers, contacts). It is clear what the tool does, though it never names or distinguishes itself from the close sibling bulk-domain-lookup.

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 singular "for a domain name" suggests one-domain lookups versus bulk-domain-lookup, and the schema warns to pass a registered domain rather than a host. There is no explicit when-to-use, when-not-to-use, or pointer to entity-lookup/asn-lookup alternatives.

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 cover safety (readOnlyHint=true, destructiveHint=false) and open-world access, so the bar is lower. The description still adds real behavioral context: the data is normalized RDAP and resolution is restricted to five specific RIR registries, which is a scoping constraint not present in the structured fields. It does not say what happens when a handle falls outside those registries.

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 with no filler. The core capability and examples come first, and the RIR limitation plus the domain-lookup redirect are packed into the second sentence.

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 single-parameter read lookup with full annotation coverage and no output schema, the description is nearly sufficient. The only gap is that it never characterizes the returned RDAP entity payload, so an agent knows what it retrieves but not what shape to expect.

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 single handle parameter is already documented with the same examples in the schema. The description repeats rather than extends that meaning, so 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 specific verb (look up) and resource (normalized RDAP data for an RIR entity handle), and immediately grounds it with concrete handle examples like "GOGL" and "ORG-RIEN1-RIPE". It also isolates itself from the closest sibling by naming domain-lookup as the tool for registrar/registrant data.

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?

Gives a clear when-not condition (only ARIN, RIPE, APNIC, LACNIC and AFRINIC handles resolve) and routes one adjacent case to domain-lookup. It does not address the other siblings (asn-lookup, ip-lookup, nameserver-lookup), so the alternative coverage is partial rather than exhaustive.

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 cover the safety profile (readOnlyHint, destructiveHint=false, openWorldHint), so the description's remaining burden is light. It still adds value by disclosing the data source ('normalized RDAP') and enumerating the fields returned, which matters given there is no output schema; it does not cover error handling or upstream rate limits.

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?

A single sentence that front-loads the verb and resource and packs the return-field list into a parenthetical. Every element earns its place with no filler.

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 two-parameter read-only lookup with annotations covering safety, the description is nearly complete: it names the data source and the returned fields, compensating for the absent output schema. It stops short of explaining error cases or how a CIDR query differs from a single-address query.

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 both parameters are already documented in the schema, establishing a baseline of 3. The phrase 'IP address or CIDR block' loosely ties the ip/prefix pair together but adds no format or constraint detail beyond what the schema states.

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 ('look up') and resource ('normalized RDAP allocation data') scoped to an IP address or CIDR block, with a parenthetical enumerating the returned fields. It is clearly distinguishable from domain-oriented siblings, though it never names or contrasts them directly.

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 resource itself — use this when you have an IP or CIDR and need allocation info. There is no explicit when-not guidance and no mention of when asn-lookup, domain-lookup or entity-lookup would be the better choice.

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 readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered structurally. The description adds that results are 'normalized RDAP data' and lists the fields returned, which is modestly useful. It does not disclose failure behavior for unknown/non-nameserver hosts or how fresh/cached the RDAP data is.

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?

One sentence, front-loaded with the verb and resource, and the parenthetical moves the returned fields out of the way. Nothing is wasted and nothing important is buried.

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 single-parameter, read-only lookup with full annotation coverage and a fully described input, the description supplies enough: scope, input type, and the shape of the returned data. Minor gaps remain around error/empty-result behavior and how this differs from the other lookup siblings.

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?

The single 'host' parameter is fully documented in the schema (100% coverage) with an example, so the description need not restate it. The phrase 'nameserver hostname' in the description reinforces the expected input 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 ('look up') and resource (RDAP data for a nameserver hostname), and enumerates the returned data points (IP addresses, status, sponsoring registrar). It is clear what the tool does, but it never contrasts itself with closely related siblings like domain-lookup or ip-lookup, leaving the agent to infer the boundary.

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?

There is no indication of when to choose this over domain-lookup, ip-lookup, or entity-lookup, nor any prerequisites or exclusions (e.g. whether the host must already be delegated). The agent gets the input shape but no routing 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 readOnly/non-destructive/closed-world, so the safety profile is covered. The description adds genuinely useful non-annotation context: the quota exemption for metadata calls, and the shape of the per-TLD answer (RDAP server, support-since date, per-field fill rates).

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?

A single front-loaded sentence carries the purpose, both modes, the return content, and the quota caveat with zero filler. The dense colon-list is still readable, and the most decision-relevant fact (metadata, no quota cost) lands before any elaboration.

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 zero-required-parameter, fully documented listing tool with no output schema, the description covers purpose, both operating modes, and quota behavior. The only modest gap is that the exact list output shape (names only vs. richer objects) is implied rather than stated, though the schema hints at 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 all three optional parameters are already documented in-schema with examples and precedence rules, so the description need not compensate. It restates the omit-to-list behavior but adds no syntax or format detail beyond the schema, warranting the baseline.

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 concrete resource (TLDs this API supports) and a concrete verb, plus two distinct modes: enumerate the set or describe a single entry. That scope is clearly distinct from every sibling (domain/ip/asn/entity/nameserver lookups), which all query records rather than enumerate API metadata.

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?

It gives clear mode-selection guidance — pass nothing to list names, or supply one TLD to describe it, with the schema reinforcing that `since` and `server` are filters ignored when `tld` is set. It stops short of naming an alternative or any when-not-to-use condition, so no explicit routing.

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