isitdns

Trace a delegation

trace

Read-onlyIdempotent

Trace a delegation from the root to the authority, like dig +trace: each referral and its glue, the one server that answered at each zone cut and any dial that failed, the final answer and its TTLs. Not for every server of a zone: sweep_domain. Each hop is asked with RD=0 over TCP from the isitdns edge or a probe, named on the hop. Give the full host name: the walk ends at the zone that answers for it, and type (default A) is what it asks there.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "name": "<name>"
    },
    "name": "trace"
  }
}

Input Schema

Name	Required	Description	Default
`name`	Yes	The name to walk. Also as "domain"; a URL is read as its host.
`type`	No	Record type for the final question	A

Output Schema

Name	Required	Description
`api`	Yes	The /api GET that asks it again, as a new reading
`trace`	Yes	query, readAt, hops, failed dials, finalAnswer, warnings
`report`	Yes	verdict, headline, steps, the TTL facts, meaning
`askAgain`	No	The isitdns.net page that asks it again, when one does
`receipts`	Yes	One per DNS read: what, of whom, from where, when, rcode, flags, EDE, ms, answer

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 9, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "api": {
+      "description": "The /api GET that asks it again, as a new reading",
+      "type": "string"
+    },
+    "askAgain": {
+      "description": "The isitdns.net page that asks it again, when one does",
+      "type": "string"
+    },
+    "receipts": {
+      "description": "One per DNS read: what, of whom, from where, when, rcode, flags, EDE, ms, answer",
+      "type": "array"
+    },
+    "report": {
+      "description": "verdict, headline, steps, the TTL facts, meaning",
+      "type": "object"
+    },
+    "trace": {
+      "description": "query, readAt, hops, failed dials, finalAnswer, warnings",
+      "type": "object"
+    }
+  },
+  "required": [
+    "report",
+    "trace",
+    "api",
+    "receipts"
+  ],
+  "type": "object"
+}

Changed1 schema field changedSep 29, 2026

changedInput schema / properties / name / description

Previous value: -"The name to walk. Also accepted as \"domain\"; a URL is reduced to its host."New value: +"The name to walk. Also as \"domain\"; a URL is read as its host."

Changed1 schema field changedSep 28, 2026

changedInput schema / properties / name / description

Previous value: -"The name to walk"New value: +"The name to walk. Also accepted as \"domain\"; a URL is reduced to its host."

First observedSep 10, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, but the description goes well beyond them: RD=0 over TCP, issued from the isitdns edge or a probe, each hop named, the walk terminating at the zone that answers, and TTLs on the final answer. Failed dials are also disclosed as part of the output, which an agent would not otherwise expect.

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

Conciseness4/5

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

Front-loaded with the core metaphor and purpose before details. The clauses are dense and comma-spliced, making it slightly hard to parse, but no sentence is redundant and the exclusion is placed early rather than buried.

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

Completeness5/5

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 explained, and the description still covers protocol, vantage points, termination condition, and failure behavior. Combined with annotations covering the safety profile, an agent has everything needed to call it correctly.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3, but the description adds genuine semantics: the name must be the full host name and determines where the walk terminates, and type applies only to the final question (default A). It also notes URLs are read as their host in the schema, not the description.

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

Purpose5/5

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

States a specific verb+resource (trace a delegation from root to authority) and immediately anchors it to a familiar analogue, dig +trace, then enumerates what the trace contains: referrals, glue, the answering server at each zone cut, failed dials, final answer and TTLs. It explicitly differentiates from the sibling sweep_domain.

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?

Gives an explicit exclusion ('Not for every server of a zone: sweep_domain') and a prerequisite ('Give the full host name'), plus the default for type. It does not disambiguate against the other closely related siblings such as dig or check_domain, which is a real gap given how similar trace and dig sound.

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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