FernTool IP Lookup

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

With no annotations, the description carries the full behavioral burden. It usefully enumerates the fields each result contains (version, scope, country, timezone, ASN, owner, flags), which is valuable since there is no output schema, but it says nothing about rate limits, auth, invalid-input handling, or partial-failure behavior in a batch call.

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 tightly written sentences with zero waste. The scope constraint is front-loaded and the return-field inventory follows immediately, making the whole definition skimmable.

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 batch tool with no output schema, the description covers purpose, cardinality, accepted formats, and return fields — enough to call it correctly. It stops short of covering error/partial-failure semantics, which is the only meaningful remaining 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 coverage is 0% and there is one parameter, so the description must compensate. It does so by clarifying the accepted format (IPv4/IPv6) and cardinality (1-100), matching the schema's minItems/maxItems constraints and adding the address-family detail the schema lacks.

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), resource (IPv4/IPv6 addresses), and scope (1-100 at once). The 'at once' phrasing plus the cardinality range lets an agent distinguish it from the sibling single-address tool lookup_ip 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?

The batch scope and 1-100 range clearly signal this is the tool for looking up many addresses, implicitly steering single-address work to lookup_ip. However, it never explicitly names an alternative or states a when-not condition, so it falls short of a full routing instruction.

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?

With no annotations, the description carries the full burden. It does add real context beyond the name — the Cloudflare 1.1.1.1 DoH backend and the 'default: all' type behavior — but says nothing about whether the operation is purely read-only, how failures (NXDOMAIN, timeouts, rate limits) surface, or what the response contains.

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 compact sentences with zero filler; the operation and backend come first, followed immediately by the parameter detail. Nothing is padded or repeated.

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?

There is no output schema and no annotations, so the description is the only source of behavioral information — yet it never describes the return shape (records, answers, TTLs) or error behavior. For a network lookup tool this leaves a meaningful 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 0%, so the description must compensate. It fully documents the 'types' parameter (allowed values plus default), though the schema enum already lists those values. The required 'domain' parameter gets no format guidance at all — subdomains, trailing dots, or IDN handling are unaddressed.

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 ('Resolve DNS records for a domain') and even names the resolver backend. It implicitly distinguishes itself from siblings like lookup_ip and reverse_dns by operating on a domain name, but never explicitly brackets what this tool is not for.

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 purpose statement — an agent can infer this is the tool for forward DNS resolution on a domain — but there is no explicit when-to-use or when-not-to-use guidance and no mention of alternatives such as reverse_dns or whois_lookup for adjacent lookups.

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?

No annotations, so the description carries the full burden; it does disclose the exact information returned and the important behavioral caveat that a remote agent sees the MCP server host's IP, not its own. It does not mention side effects, rate limits, or whether the lookup requires external network access, which a no-annotation read tool ideally would.

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, no filler, with the return-value summary and the caller-scoping caveat front-loaded in that order. 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?

There is no output schema, so the description appropriately enumerates the return fields, and the remote-agent caveat covers the one ambiguity that would otherwise cause misuse. Nothing needed to call it correctly is missing.

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 tool takes zero parameters, so there is no parameter semantics to explain; the baseline for a 0-param tool is 4. The description correctly implies no arguments are needed.

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?

Specific verb+resource ('Return the public IP address... of the caller') and enumerates the returned fields (ISP, ASN, location, timezone). This implicitly but clearly separates it from lookup_ip/batch_lookup_ip, which look up arbitrary addresses rather than the caller's own.

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?

"of the caller" establishes the condition that selects this tool over the sibling lookup_ip/whois_lookup tools, and the remote-agent note clarifies when the result may be surprising. It stops short of explicitly naming an alternative or stating when not to use it.

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?

With no annotations, the description carries the full disclosure burden. It usefully names the data sources (DB-IP Lite, IPtoASN) and enumerates returned fields, which signals a read-only enrichment lookup, but it omits rate limits, behavior on unparseable input, and whether a lookup can fail for unknown addresses.

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 dense sentence that front-loads the action and then lists the return payload, with the parenthetical source attribution adding provenance rather than noise. Nothing is redundant, though the enumeration is long enough that it borders on cramming several payload concepts into one clause.

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 correctly compensates by enumerating the returned fields (version, scope, country, ASN, owner). It is nearly complete for a one-parameter lookup, missing only edge-case behavior such as invalid-IP errors or unresolvable private-range lookups.

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 'ip' parameter is already documented as 'IPv4 or IPv6 address'. The description restates the same accepted formats without adding syntax, normalization, or CIDR-handling detail, so the schema does the heavy lifting and 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?

The description gives a specific verb and resource plus an explicit return payload (version, scope, country, ASN, owner), so the enrichment intent is clear. It fails to differentiate from siblings, however: it leads with 'Validate', which overlaps directly with the sibling validate_ip, and the ASN/owner data also overlaps with whois_lookup, so an agent cannot cleanly separate this tool from those without inspecting schemas.

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 statement of when to use this tool versus validate_ip, whois_lookup, batch_lookup_ip, or get_my_ip. The only cue is implicit in the return fields. An agent gets no explicit routing guidance despite a crowded sibling set with adjacent purposes.

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?

With no annotations, the description must carry the behavioral burden. It does disclose a non-obvious trait: the forward-confirmation check (FCrDNS), which hints at extra work and a possible mismatch result. It says nothing about failure behavior when no PTR or FC mismatch occurs, nor about latency or 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?

One sentence, front-loaded with the operation, with zero filler. Every clause (reverse/PTR, IPv4/IPv6, forward-confirmation) 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?

No output schema and no annotations, so the description is the only source of information. It does not say what is returned (PTR hostname, FC confirmation status, what a mismatch looks like), which an agent needs to interpret results for a lookup tool.

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 0% and the lone 'ip' parameter is only typed as string, so the description must compensate. It does, by specifying that the accepted values are IPv4 or IPv6 addresses, which the schema does not say. That is meaningful added semantics for a single trivial 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?

States a specific verb and resource: a reverse DNS (PTR) lookup for an IPv4/IPv6 address. That is far more precise than the sibling names lookup_ip or dns_lookup, though it never explicitly names those siblings to disambiguate the forward-vs-reverse distinction.

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 'reverse DNS (PTR) lookup' versus the forward-looking dns_lookup sibling, but there is no explicit when-to-use or when-not-to-use statement and no alternative named. An agent can infer the intent but gets 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?

No annotations are provided, so the description carries the full behavioral burden. It discloses the computation's outputs (netmask, wildcard, broadcast, usable host range, block type), which is useful, but says nothing about whether it is a pure local calculation with no side effects, how malformed CIDRs (e.g. host bits set) are handled, or whether it performs any network I/O.

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 front-loaded sentence: the tool identity comes first, followed by a dense but purposeful list of outputs. Nothing is redundant, and the enumeration substitutes usefully for the missing 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?

With no output schema, the description appropriately enumerates the return fields, and the single input is fully specified by the schema. Only minor gaps remain, such as error behavior on invalid or non-canonical CIDR input.

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 a single required parameter at 100% schema description coverage, and the schema already gives format examples ('192.168.1.0/24 or 2001:db8::/48'). The description adds no further syntax or normalization details, 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+resource ('CIDR subnet calculator') covering both IPv4 and IPv6, and enumerates the computed outputs. It is clearly distinct from its lookup/validation siblings like lookup_ip and validate_ip, though it never explicitly contrasts itself with them.

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?

No when-to-use guidance, no prerequisites, and no mention of alternatives such as validate_ip or lookup_ip. The only implied usage is that the caller supplies a CIDR string, which the schema already enforces via the required 'cidr' parameter.

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?

With no annotations, the description must carry the behavioral burden. The phrasing 'Check whether' implies a side-effect-free read, and it discloses accepted formats (IPv4/IPv6), but it says nothing about the return shape, whether it rejects malformed input or returns false, or what 'classify' means.

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 tight sentence with the operation front-loaded and no filler. Every clause ('valid IPv4 or IPv6', 'classify it') contributes meaning.

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 trivial one-param function this is close to adequate, but since there is no output schema the description should specify what 'classify' returns (e.g. private/public/loopback) and how invalid input is reported. Those gaps matter more because no structured field fills them.

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 parameter has 0% schema description coverage, so the schema only tells the agent the input is a string. The description compensates partially by stating the string should be an IPv4 or IPv6 address, but adds no syntax details (CIDR, port suffixes, leading zeros).

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 ('Check whether') and resource ('a string is a valid IPv4 or IPv6 address') plus the extra outcome ('classify it'). This distinguishes it functionally from the lookup/dns/whois siblings, but the description never names an alternative, so sibling differentiation is 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?

There is no guidance on when to call this versus lookup_ip, subnet_calc, or dns_lookup. An agent could reasonably wonder whether validate_ip also returns metadata or handles CIDR notation, and the description leaves that 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?

With no annotations, the description carries the full burden, and it does disclose per-input return content (registrar, created/expiry, status, nameservers, DNSSEC; network range, org, country, abuse contact). It omits operational behavior such as rate limiting, lookup failures for unregistered domains, or RDAP server coverage. For a low-risk public read, this is solid but not exhaustive.

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 with the resource type stated first and the parenthetical field lists carrying dense, non-redundant detail. No filler or repetition.

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 only one parameter, no annotations, and no output schema, the description's enumeration of returned fields is what makes the tool usable without a return schema. It is nearly complete, losing only on unsupported-lookup or rate-limit behavior.

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?

One parameter with 100% schema description coverage, so the schema already documents that 'query' accepts a domain, IPv4/IPv6, or ASN with the AS13335 example. The description restates this same information rather than adding format constraints or normalization rules, so it adds little 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?

The description names a specific verb (WHOIS via RDAP) and enumerates the three resource types it accepts and the exact fields it returns for each, so the purpose is unambiguous. It does not, however, reference any sibling tool (e.g. lookup_ip, reverse_dns, dns_lookup), so an agent must infer the boundary from the RDAP field list alone.

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 accepted input forms (domain, IP, ASN) suggest when the tool applies, but there is no explicit statement of when to prefer it over lookup_ip or dns_lookup, and no mention of exclusions or prerequisites. No guidance on invalid input or unsupported TLDs either.

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