DomainDNA

Email provider, SPF and DMARC

email_security

Read-onlyIdempotent

Email and DNS setup only, for 1-5 domains. Use this when you need to check email deliverability or spoofing protection, or to see which email provider (Google Workspace, Microsoft 365…) a company uses. Does not fetch the website (use tech_stack) or registration data (use domain_registration). Input: domains (1-5 domains, URLs or email addresses). Returns results[] with, per domain: exists; email (MX hosts and provider, SPF record and its all qualifier, DMARC policy, pct and rua); dns (A/AAAA/NS records); verifications (services proven by TXT site-verification tokens, e.g. google, apple, atlassian); errors, analyzedAt and cached. Limits: each domain counts as one lookup; answers cached for 1 hour per domain; 25 free domains a day per IP without a key, more with a paid key in the x-api-key header. Read-only: nothing is stored, no email is sent.

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": {
      "domains": "<domains>"
    },
    "name": "email_security"
  }
}

Input Schema

Name	Required	Description	Default
`domains`	Yes	1-5 domains, website URLs or email addresses (the domain part is used)

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedOct 11, 2026

addedInput schema / additionalProperties
```
Added value: +false
```

changedInput schema / properties / domains / description

Previous value: -"1-5 domains, URLs or email addresses, e.g. [\"stripe.com\", \"shopify.com\"]"New value: +"1-5 domains, website URLs or email addresses (the domain part is used)"

addedInput schema / properties / domains / examples

Added value: +[
+  [
+    "stripe.com",
+    "shopify.com"
+  ]
+]

Changed1 schema field changedOct 9, 2026

addedInput schema / properties / domains / description

Added value: +"1-5 domains, URLs or email addresses, e.g. [\"stripe.com\", \"shopify.com\"]"

First observedOct 1, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Annotations already declare read-only, idempotent, open-world and non-destructive, so the safety profile is covered; the description goes further by disclosing per-domain lookup accounting, a 1-hour per-domain cache, the 25 free domains/day per IP quota, the x-api-key header for paid keys, and that nothing is stored or emailed.

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 purpose and routing before details, and the limits/auth/read-only facts all earn their place. The 'Input: domains (1-5 domains, URLs or email addresses)' clause is mildly redundant with the schema, keeping it just short of 5.

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?

With no output schema, the description usefully enumerates the return shape (results[] with exists, email, dns, verifications, errors, analyzedAt, cached) and covers quota and auth. 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.

Parameters3/5

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

Schema description coverage is 100% for the single `domains` parameter, so the baseline is 3. The description restates the same 1-5 domain / URL-or-email constraint the schema already documents, adding no new syntax or format meaning.

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 and resource ('check email deliverability or spoofing protection', 'see which email provider a company uses') and explicitly names the sibling tools it is not (tech_stack, domain_registration). An agent can distinguish it from all three siblings without opening a schema.

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?

Gives explicit when-to-use triggers (deliverability, spoofing protection, provider identification) and explicit when-not alternatives, routing website lookups to tech_stack and registration data to domain_registration. Nothing is left to inference.

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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