woow_emqx_mcp_server

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Delete Retained Message

emqx_delete_retained

DestructiveIdempotent

Delete a stale retained message for a topic to remove outdated Home Assistant discovery entries or ghost device states. This action is permanent.

Instructions

[DESTRUCTIVE] Delete the retained message for one topic.

This is the correct way to remove a stale Home Assistant discovery entry or a ghost device state. It cannot be undone — the previous payload is gone unless something republishes it.

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>"
    },
    "name": "emqx_delete_retained"
  }
}

Input Schema

Name	Required	Description	Default
`topic`	Yes	Exact topic whose retained message to remove.

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 3, 2026

TDQS

A4.5/5.0

Behavior5/5

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

The description goes beyond the annotations by explicitly stating the irreversible consequence: 'It cannot be undone — the previous payload is gone unless something republishes it.' It also opens with [DESTRUCTIVE], reinforcing the destructive nature.

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 two concise sentences: the first states the action, the second provides a use case and consequence. It is front-loaded with a destructive warning and has no wasted words.

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 only one parameter, full schema coverage, and an output schema present, the description covers the purpose, use case, and irreversible nature. No significant gaps remain.

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 input schema already fully describes the single `topic` parameter with 'Exact topic whose retained message to remove.' The description adds no additional parameter semantics, so the baseline of 3 applies due to 100% schema coverage.

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 verb and resource: 'Delete the retained message for one topic.' It clearly distinguishes this tool from sibling tools like emqx_get_retained and emqx_list_retained by focusing on deletion.

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 provides a concrete use case: removing stale Home Assistant discovery entries or ghost device states. It implies when to use it but does not explicitly mention alternatives or when not to use it, so it stops short of a 5.

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