listmonk-mcp

Test SMTP connection

listmonk_smtp_test

Sends a real test email through a specified SMTP server to verify configuration and diagnose delivery issues.

Instructions

Opens a connection to a configured SMTP server and sends a test email to the given address. Sends real mail through the instance's SMTP settings.

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": {
      "email": "<email>",
      "smtp_index": "<smtp_index>"
    },
    "name": "listmonk_smtp_test"
  }
}

Input Schema

Name	Required	Description	Default
`email`	Yes	Address to receive the test email
`smtp_index`	Yes	Index of the SMTP server in settings (0 = first)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 1, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already establish that this is not read-only, is open-world, and is non-idempotent. The description adds useful behavioral context by explicitly warning that it sends real mail through the instance's SMTP settings.

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 concise sentences, front-loaded with the core action and followed by the key side-effect warning. No unnecessary wording.

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?

For a two-parameter test tool with full schema coverage and relevant annotations, the description covers purpose and side effect. It does not explain return behavior, but no output schema exists and the omission is minor.

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?

The schema has 100% description coverage for both parameters, so the baseline is 3. The description mentions the email address and configured SMTP server but adds no syntax, indexing, or format details beyond the schema.

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 action: open an SMTP connection and send a test email to a given address. It clearly identifies the resource as the configured SMTP server, which distinguishes it from campaign-oriented test-send tools.

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?

It implies the tool is for testing SMTP configuration by sending real mail, but does not explicitly say when to use it versus siblings like campaign_test_send or what conditions should exclude its use.

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