isitdns

dig

dig

Read-onlyIdempotent

Use for one exact question to one public resolver, not as the first call for a site that is not working. Returns records, flags, rcode, EDE and latency; DoH from the edge, or Do53 from a region's probe (from).

Input Schema

TableJSON Schema

Name	Required	Description	Default
`cd`	No	Ask the resolver not to validate
`ecs`	No	EDNS Client Subnet, e.g. 192.0.2.0/24
`from`	No	Ask from the probe in this region
`name`	Yes	The name, e.g. _dmarc.example.com. Also as "domain"; a URL is read as its host.
`nsid`	No	Request NSID (RFC 5001)
`type`	No	Record type, e.g. A, MX, TXT, DS, HTTPS, or TYPE<n>	A
`norec`	No	Clear RD, like dig +norec
`dnssec`	No	Set the DO bit and read AD
`family`	No	Address family to dial	v4
`resolver`	No	A board resolver id (cloudflare, google, quad9, opendns, adguard, cleanbrowsing, controld, quad9-unfiltered, adguard-family, cleanbrowsing-family, adguard-unfiltered, opendns-familyshield, nextdns, cloudflare-malware, cloudflare-family, mullvad-base, dns4eu-protective), an alias such as 8.8.8.8, or all for the tier-1 operators side by side.	cloudflare

Schema Changelog

Changes observed during successful MCP inspections.

Changed6 schema fields changedSep 29, 2026

changedInput schema / properties / cd / description

Previous value: -"Checking disabled: ask the resolver not to validate"New value: +"Ask the resolver not to validate"

changedInput schema / properties / ecs / description

Previous value: -"EDNS Client Subnet in CIDR form, e.g. 192.0.2.0/24"New value: +"EDNS Client Subnet, e.g. 192.0.2.0/24"

changedInput schema / properties / family / description

Previous value: -"Which address family to dial the resolver on"New value: +"Address family to dial"

addedInput schema / properties / from

Added value: +{
+  "description": "Ask from the probe in this region",
+  "enum": [
+    "north-america",
+    "europe"
+  ],
+  "type": "string"
+}

changedInput schema / properties / name / description

Previous value: -"The name to ask for, e.g. example.com or _dmarc.example.com. Also accepted as \"domain\"; a URL is reduced to its host."New value: +"The name, e.g. _dmarc.example.com. Also as \"domain\"; a URL is read as its host."

changedInput schema / properties / type / description

Previous value: -"Record type: A, AAAA, MX, TXT, NS, SOA, CNAME, DS, DNSKEY, CAA, SRV, HTTPS, SVCB, PTR, or TYPE<n>"New value: +"Record type, e.g. A, MX, TXT, DS, HTTPS, or TYPE<n>"

Changed1 schema field changedSep 29, 2026

changedInput schema / properties / resolver / description

Previous value: -"A board resolver id (cloudflare, google, quad9, opendns, adguard, cleanbrowsing, controld, quad9-unfiltered, adguard-family, cleanbrowsing-family, adguard-unfiltered, opendns-familyshield, nextdns, cloudflare-malware, cloudflare-family, mullvad-base, dns4eu-protective), a registry alias such as 8.8.8.8 or dns.google, or \"all\" for the tier-1 operators side by side (cloudflare, google, quad9, adguard). An address that is not on the board is refused here with the HTTP URL that can dial it."New value: +"A board resolver id (cloudflare, google, quad9, opendns, adguard, cleanbrowsing, controld, quad9-unfiltered, adguard-family, cleanbrowsing-family, adguard-unfiltered, opendns-familyshield, nextdns, cloudflare-malware, cloudflare-family, mullvad-base, dns4eu-protective), an alias such as 8.8.8.8, or all for the tier-1 operators side by side."

Changed1 schema field changedSep 28, 2026

changedInput schema / properties / name / description

Previous value: -"The name to ask for, e.g. example.com or _dmarc.example.com"New value: +"The name to ask for, e.g. example.com or _dmarc.example.com. Also accepted as \"domain\"; a URL is reduced to its host."

Changed1 schema field changedSep 27, 2026

changedInput schema / properties / resolver / description

Previous value: -"A board resolver id (cloudflare, google, quad9, opendns, adguard, cleanbrowsing, controld, quad9-unfiltered, adguard-family, cleanbrowsing-family, adguard-unfiltered, opendns-familyshield, nextdns, cloudflare-malware, cloudflare-family, mullvad-base, dns4eu-protective), a registry alias such as 8.8.8.8 or dns.google, or \"all\" for every public resolver side by side. An address that is not on the board is refused here with the HTTP URL that can dial it."New value: +"A board resolver id (cloudflare, google, quad9, opendns, adguard, cleanbrowsing, controld, quad9-unfiltered, adguard-family, cleanbrowsing-family, adguard-unfiltered, opendns-familyshield, nextdns, cloudflare-malware, cloudflare-family, mullvad-base, dns4eu-protective), a registry alias such as 8.8.8.8 or dns.google, or \"all\" for the tier-1 operators side by side (cloudflare, google, quad9, adguard). An address that is not on the board is refused here with the HTTP URL that can dial it."

Changed3 schema fields changedSep 27, 2026

changedInput schema / properties / norec / description

Previous value: -"Clear RD, like dig +norec, when asking an authoritative server directly"New value: +"Clear RD, like dig +norec"

changedInput schema / properties / resolver / description

Previous value: -"A board resolver id (cloudflare, google, quad9, opendns, adguard, cleanbrowsing, controld, quad9-unfiltered, adguard-family, cleanbrowsing-family, adguard-unfiltered, opendns-familyshield, nextdns, cloudflare-malware, cloudflare-family, mullvad-base, dns4eu-protective), a registry alias such as 8.8.8.8 or dns.google, \"all\" for every public resolver side by side, or any public IP address"New value: +"A board resolver id (cloudflare, google, quad9, opendns, adguard, cleanbrowsing, controld, quad9-unfiltered, adguard-family, cleanbrowsing-family, adguard-unfiltered, opendns-familyshield, nextdns, cloudflare-malware, cloudflare-family, mullvad-base, dns4eu-protective), a registry alias such as 8.8.8.8 or dns.google, or \"all\" for every public resolver side by side. An address that is not on the board is refused here with the HTTP URL that can dial it."

removedInput schema / properties / transport

Removed value: -{
-  "default": "doh",
-  "description": "DoH (RFC 8484 wire format), DoT on 853, Do53 over TCP, or Do53 over UDP. udp53 is the transport the Cloudflare edge cannot run, so it is measured from our own probe off Cloudflare (each result says which seat measured it in vantage) and it carries RD and DNSSEC only: +cd, ECS and NSID are refused rather than dropped.",
-  "enum": [
-    "doh",
-    "dot",
-    "tcp53",
-    "udp53"
-  ],
-  "type": "string"
-}

Changed2 schema fields changedSep 12, 2026

changedInput schema / properties / transport / description

Previous value: -"DoH (RFC 8484 wire format), DoT on 853, or Do53 over TCP"New value: +"DoH (RFC 8484 wire format), DoT on 853, Do53 over TCP, or Do53 over UDP. udp53 is the transport the Cloudflare edge cannot run, so it is measured from our own probe off Cloudflare (each result says which seat measured it in vantage) and it carries RD and DNSSEC only: +cd, ECS and NSID are refused rather than dropped."

changedInput schema / properties / transport / enum

Previous value: -[
-  "doh",
-  "dot",
-  "tcp53"
-]New value: +[
+  "doh",
+  "dot",
+  "tcp53",
+  "udp53"
+]

First observedSep 10, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent and openWorld, so safety is covered. The description adds genuine context beyond them: the returned fields (records, flags, rcode, EDE, latency) and the transport distinction (DoH from the edge vs Do53 from a region probe via 'from'). It omits rate limits or failure behavior, so not a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences with zero padding, and the usage guidance is front-loaded before the output details. Every clause carries information an agent needs.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema and 10 parameters, the description does well to summarize the return payload and the edge-vs-probe behavior. It never explains resolver='all' or the interaction between dnssec/cd, but the 100% schema coverage absorbs most of that gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so every parameter including the resolver board list is already documented in the schema, setting the baseline at 3. The description only adds meaningful color to the 'from' parameter (regional probe / Do53), leaving resolver, family, type, dnssec and the boolean flags entirely to the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific action (one exact question to one public resolver) and the resource (DNS records), which is clearly distinct from diagnostics suites like trace or alias_chain. It does not name a sibling directly, but the scope is unambiguous enough to route correctly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly gives both when to use (a single exact lookup) and when not ('not as the first call for a site that is not working'), which steers agents away from it for broad diagnostics. It stops short of naming the alternative sibling (e.g. check_domain or trace) that should be called first.

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

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