netdiag-mcp

dns_lookup

Resolve any DNS record type (A, AAAA, MX, TXT, etc.) using dig, with optional resolver and transport selection to verify propagation.

Instructions

Resolve a DNS record via dig. record_type: A/AAAA/MX/TXT/NS/CNAME/SOA/PTR/CAA.

Pass resolver to query a specific nameserver instead of the host default (e.g. to check whether a change has propagated to a given resolver). transport: "plain" (UDP/TCP 53, default), "dot" (DNS-over-TLS, 853) or "doh" (DNS-over-HTTPS, 443). Requires dig from BIND 9.18+; an older dig rejects dot/doh outright instead of silently querying over plain DNS.

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": {
      "hostname": "<hostname>"
    },
    "name": "dns_lookup"
  }
}

Input Schema

Name	Required	Default
`hostname`	Yes
`resolver`	No
`transport`	No	plain
`record_type`	No	A

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 30, 2026

TDQS

A4.4/5.0

Behavior4/5

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

With no annotations, the description carries the behavioral transparency burden. It discloses transport behavior, default ports, and the critical dependency on dig BIND 9.18+, including how older dig versions fail. It does not cover every edge case, but the important behavioral quirks are transparent.

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?

The description is dense but purposeful, with each sentence adding meaningful technical information. It front-loads the core action, then organizes parameter details and dependency caveats cleanly. No filler or redundant restatement of the name.

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?

Given an output schema exists, return values are covered elsewhere. The description adds essential context about transports, resolvers, and the dig version requirement. It is complete enough for correct invocation, though it could mention edge cases like PTR record hostname formatting or timeout behavior.

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 description coverage is 0%, so the description must explain the parameters, and it largely does. It enumerates record_type values, defines resolver usage, and clarifies transport options with ports and defaults. Hostname is left implicit, but that is a well-understood parameter for a DNS lookup tool.

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?

The description opens with a specific verb and resource: 'Resolve a DNS record via `dig`.' It lists supported record types and clearly distinguishes itself from sibling tools like dnssec_check, whois_lookup, and asn_lookup. An agent can immediately tell what this tool does.

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?

The description explains when to use the resolver parameter, such as checking whether a change has propagated to a given resolver. It gives clear operational context, though it does not explicitly contrast with sibling tools or state when not to use it. Overall, usage intent is well implied.

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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