listmonk-mcp

Send transactional email

tx_send

Sends one transactional email from a Listmonk 'tx' template to a subscriber, filling placeholders with provided data. Use for real account or order notifications.

Instructions

Send one transactional email from a 'tx' template to a subscriber email. data fills template placeholders. Sends real mail.

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": {
      "template_id": "<template_id>",
      "subscriber_email": "<subscriber_email>"
    },
    "name": "tx_send"
  }
}

Input Schema

Name	Required	Default
`data`	No
`subject`	No
`from_email`	No
`template_id`	Yes
`content_type`	No	html
`subscriber_email`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 1, 2026

TDQS

B3.2/5.0

Behavior3/5

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

The annotations already disclose readOnly=false, openWorld=true, and idempotent=false. The description adds a valuable warning that this 'Sends real mail', but it does not mention duplicate-send risk, rate limits, permissions, or irrevocability beyond what the annotations already imply.

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?

Three short sentences, front-loaded with purpose and ending with the most important operational warning. There is no padding.

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

Completeness2/5

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

This is a six-parameter, open-world mutation tool with no output schema and no parameter descriptions. The description omits required-field semantics, override behavior for subject/from_email/content_type, and concrete side-effect detail, leaving the agent under-informed.

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

Parameters2/5

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

Schema description coverage is 0%, so the description must carry parameter meaning. It only explains that 'data' fills template placeholders and does not clarify template_id, subscriber_email, subject, from_email, content_type options, or expected nested data shape.

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 states a specific verb ('Send') and resource ('one transactional email'), and clarifies it uses a 'tx' template aimed at a subscriber email. That distinguishes it reasonably well from campaign_test_send and campaign-oriented siblings, though it does not explicitly name those alternatives.

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 this is for real transactional sends rather than tests ('Sends real mail'), which is useful context. However, it does not explicitly say when to use this versus campaign_test_send or other send-related siblings, nor does it state prerequisites or exclusions.

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