Mailcannon

check_domain_deliverability

Check SPF, DKIM, DMARC records for a domain

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": {
      "domain": "<domain>"
    },
    "name": "check_domain_deliverability"
  }
}

Input Schema

Name	Required	Description	Default
`domain`	Yes	Domain to check (e.g. thinkandautomate.dev)

Schema Changelog

Changes observed during successful MCP inspections.

First observedJul 25, 2026

TDQS

A3.6/5.0

Behavior3/5

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

No annotations are provided, so the description carries the burden of explaining behavior. It identifies the specific records checked but does not disclose whether the tool performs a live DNS lookup, returns a simple pass/fail, or provides detailed output. It does not explicitly state read-only behavior, though it is implied by 'check'.

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?

A single, concise sentence that communicates the core function without redundant words or filler. It is well-front-loaded and easy to parse.

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

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple one-parameter tool, the description is adequate but leaves gaps: no mention of output format (e.g., boolean vs. detailed report), no context on when to choose this over get_deliverability, and no note on potential failure modes. Lacking an output schema, some of this information would be helpful.

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?

The schema already describes the domain parameter with an example (100% coverage), so the baseline is 3. The description adds value by specifying exactly which DNS records (SPF, DKIM, DMARC) are evaluated, giving the domain parameter more operational meaning.

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

Purpose4/5

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

The description clearly states the tool checks SPF, DKIM, and DMARC records for a domain, using a specific verb and resource. It does not explicitly differentiate from sibling tools like get_deliverability or check_email_spam_score, but the specific mention of the three record types gives enough clarity.

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

Usage Guidelines3/5

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

Usage is implied: this tool is for verifying email authentication records for a domain. However, there is no explicit when-to-use vs. alternatives guidance, particularly compared to get_deliverability, which might be a similar or higher-level tool.

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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