Skip to main content
Glama
dnsdoctor

DNS Doctor

by dnsdoctor
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript

check_dkim_selector

Read-onlyIdempotent

Verify whether a specific DKIM selector exists for a domain and diagnose why DKIM authentication fails. Returns verdict, explanation, and published key record to confirm the sending platform's setup.

Instructions

Use this when the user asks whether DKIM is set up for a sending platform, whether a specific selector exists, or why DKIM fails. Check ONE specific DKIM selector on a domain — the exact selector the sending platform uses (e.g. google, s1), which a full scan's common-selector sweep may miss. Returns the verdict, its explanation, and the published key record when one resolves. No fix record is returned: a DKIM key is generated by the sending platform, so the fix is always to publish what that platform gives the owner.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
domainYesThe domain to check, e.g. example.com. Bare registrable names and subdomains both work; scheme, path or port do not belong here. Unicode names are accepted and normalized to punycode.
selectorYesThe DKIM selector to probe — the name before ._domainkey, e.g. 'google', 'selector1', or a dotted form like 's1.prod'. The sending platform's settings page names it; it is not guessable from the domain.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changedv1.2.1
    • addedInput schema / properties / domain / description
      Added value: +"The domain to check, e.g. example.com. Bare registrable names and subdomains both work; scheme, path or port do not belong here. Unicode names are accepted and normalized to punycode."
    • addedInput schema / properties / selector / description
      Added value: +"The DKIM selector to probe — the name before ._domainkey, e.g. 'google', 'selector1', or a dotted form like 's1.prod'. The sending platform's settings page names it; it is not guessable from the domain."
  2. First observedv0.1.0

TDQS

A4.9/5.0
Behavior5/5

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

Annotations already indicate readOnly, openWorld, idempotent, and non-destructive behavior. The description adds meaningful behavioral context by stating exactly what is returned (verdict, explanation, published key record when present) and explicitly noting that no fix record is returned and why. This goes beyond the annotations without contradicting them.

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 four sentences with no filler. It front-loads the usage trigger, defines the operational scope, states the return payload, and explains the absence of a fix record. Every sentence earns its place.

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?

For a two-parameter tool with fully documented schema properties and non-destructive annotations, this description is complete. It covers when to use it, what the parameters mean in practice, what the response will contain, and what it will not contain. No important gap remains for an agent to invoke 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 strong. The description adds value by emphasizing that the selector must be the exact value the sending platform uses, that it is not guessable from the domain, and that the common-selector sweep in a full scan may miss it. This supplements the schema's examples and clarifies the key selection behavior.

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 states a specific verb and resource: checking one specific DKIM selector on a domain, and ties it directly to user intents like 'is DKIM set up' or 'does this selector exist.' It also differentiates itself from a full scan's common-selector sweep, making its scope clear relative to sibling tools.

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

Usage Guidelines5/5

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

The opening line explicitly says when to use this tool: when the user asks whether DKIM is set up, whether a specific selector exists, or why DKIM fails. It also explains the limitation of a full scan's common-selector sweep, giving the agent a concrete basis for choosing this tool over scan_domain.

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

Deploy Server

Other Tools