debmatic-mcp

Set System Variable

set_system_variable

DestructiveIdempotent

Update HomeMatic system variables by assigning a new value with automatic type detection. Use list_system_variables to see available variables.

Instructions

Set a system variable value. Type is auto-detected — use list_system_variables to see available variables.

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": {
      "name": "<name>",
      "value": "<value>"
    },
    "name": "set_system_variable"
  }
}

Input Schema

Name	Required	Description
`name`	Yes	Variable name (exact match)
`value`	Yes	Value to set
`confirm`	No	Set true to authorize this write against a protected CCU target (e.g. prod). Unlocks writes to that target for the rest of the session.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv1.11.0Sep 2, 2026

removedInput schema / properties / value / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "number"
-  },
-  {
-    "type": "boolean"
-  }
-]

addedInput schema / properties / value / type

Added value: +[
+  "string",
+  "number",
+  "boolean"
+]

Changed1 schema field changedv1.7.0Jul 4, 2026

addedInput schema / properties / confirm

Added value: +{
+  "description": "Set true to authorize this write against a protected CCU target (e.g. prod). Unlocks writes to that target for the rest of the session.",
+  "type": "boolean"
+}

First observedv1.1.2Jun 11, 2026

TDQS

A3.6/5.0

Behavior3/5

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

The annotations already declare the operation destructive, idempotent, and open-world. The description adds one behavioral detail beyond that: type auto-detection. It does not mention overwrite semantics or the protected-target confirmation behavior, though the confirm parameter schema covers that context.

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 a single front-loaded sentence that states the operation and immediately provides the most useful usage hint. There is no redundant repetition of schema information.

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 destructive write with a confirmation parameter, the description is somewhat thin: it relies on the schema for protected-target behavior and does not clarify when to use it versus set_value or put_paramset. Still, annotations and a fully described schema make the tool callable without fatal gaps.

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?

Schema coverage is 100%, so the baseline is 3, but the description adds value: 'use list_system_variables to see available variables' helps supply a dynamic value for the name parameter, and 'Type is auto-detected' clarifies how the value union is interpreted. The confirm parameter is already well described in the schema.

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 names a specific action ('Set') and resource ('a system variable value'), distinguishing it from create_system_variable and delete_system_variable. However, it does not explicitly state that it modifies an existing variable or differentiate it from the sibling set_value tool.

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?

The description gives one useful routing cue: 'use list_system_variables to see available variables' for discovering valid names. It does not say when to prefer this tool over set_value or put_paramset, nor does it give an explicit when-not-to-use case.

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