mqtt-mcp-server

publish

Transmit MQTT messages to specified topics, with optional QoS and retain flags. Respects write mode restrictions and topic blocklists to avoid unintended transmissions.

Instructions

Nachricht senden. Nur bei aktivem Schreibmodus und nicht auf gesperrte Topics.

⚠️ Die Sperrliste ist eine Bremse gegen Fehlgriffe, keine Sicherheitsgrenze.

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": {
      "topic": "<topic>",
      "payload": "<payload>"
    },
    "name": "publish"
  }
}

Input Schema

Name	Required	Description	Default
`qos`	No
`topic`	Yes
`retain`	No
`payload`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 1, 2026

TDQS

A3.5/5.0

Behavior3/5

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

With no annotations provided, the description carries the full burden. It discloses that the tool enforces write-mode and topic-lock constraints, and the warning about the blocklist being a brake, not a security boundary, adds nuanced behavioral context. However, it does not describe failure behavior, side effects, or the outcome of publishing, leaving significant gaps.

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?

The description is only two short sentences, wastes no words, and front-loads the core action ('Nachricht senden') followed by essential constraints. Every sentence contributes meaningful information.

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?

Although an output schema exists and the tool is conceptually simple, the description lacks parameter guidance and sufficient behavioral detail. With no annotations and no parameter descriptions, this sparse description is inadequate for an agent to ensure correct invocation, especially concerning optional parameters and error cases.

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

Parameters1/5

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

Schema description coverage is 0%, and the description does not mention any parameter (topic, payload, qos, retain). The description provides no additional meaning beyond the raw parameter names, which is especially problematic for qos and retain that have domain-specific semantics.

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 'Nachricht senden' (send message), which is a specific verb and resource. This clearly distinguishes it from sibling tools like list_topics, get_last, and get_history, which are all read-oriented.

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?

The description explicitly states the conditions for use: 'Nur bei aktivem Schreibmodus und nicht auf gesperrte Topics' (Only with active write mode and not on locked topics). This gives clear context for when the tool can be used, though it does not explicitly mention alternatives or exclusions beyond these conditions.

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

Deploy Server