scan.mx Email Diagnostics

Check DKIM

check_dkim

Read-only

Check DKIM signing keys for a domain. Without a selector, common provider selectors are probed. Pass an explicit selector to look up that exact key at selector._domainkey.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`domain`	Yes	The domain to check, e.g. example.com. No scheme or path.
`selector`	No	An explicit DKIM selector to look up (e.g. "google", "s1").

Output Schema

TableJSON Schema

Name	Required	Description	Default
`grade`	No
`score`	No
`checks`	No
`domain`	Yes
`provider`	No
`sections`	No
`selector`	No
`permalink`	No
`smtp_note`	No
`created_at`	No
`expires_at`	No
`updated_at`	No
`smtp_status`	No
`poll_after_seconds`	No

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

Changed1 schema field changedJul 10, 2026
- addedInput schema / properties / selector / pattern
```
Added value: +"^[a-z0-9_.-]+$"
```
First observedJul 9, 2026

TDQS

A4.6/5.0

Behavior4/5

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

Annotations declare readOnlyHint and openWorldHint. Description adds meaningful behavior: probing common selectors by default and exact lookup with explicit selector. This goes beyond annotations, though could detail probed selectors.

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 efficient, front-loaded information. Every word adds value, no redundancy.

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 output schema present, description covers the tool's purpose and parameter behavior comprehensively. Annotations and sibling context complete the picture.

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

Parameters5/5

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

Description adds significant value beyond schema descriptions: it explains the default probing behavior when selector is omitted and the exact lookup when provided. This clarifies parameter interplay.

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?

Description clearly states it checks DKIM signing keys for a domain, and explains two modes: probing common selectors or using an explicit selector. This distinguishes it from sibling tools like check_spf, check_dmarc, etc.

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?

Description indicates when to use the tool (to check DKIM keys) and how to customize with the selector parameter. It could explicitly mention alternatives but is clear enough for selection among siblings.

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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TDQS

A4.3/5.0

Disambiguation5/5

Each tool targets a distinct deliverability concern: blacklist status, DKIM, DMARC, full domain scan, MX, and SPF. There is no overlap in functionality; even check_domain's comprehensive check is clearly differentiated from the individual checks.

Naming Consistency5/5

All tools follow a consistent check_[resource] naming pattern (e.g., check_blacklist, check_dkim, check_dmarc). This pattern is uniform and predictable, making it easy for an agent to infer tool purposes.

Tool Count5/5

Six tools is an ideal scope for an email diagnostics server. Each tool covers a core aspect of deliverability (MX, SPF, DKIM, DMARC, blacklists, and a full scan), with no redundancy. The count feels complete and focused.

Completeness4/5

The tool set covers the major email deliverability checks (MX, SPF, DKIM, DMARC, blacklists, and a full domain scan with optional SMTP probe). A minor gap might be the lack of a dedicated tool for SPF or DKIM record modification, but for a diagnostic-only server, the coverage is robust and actionable.

Resources

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