vlc-mcp

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adjust_volume

Increase or decrease VLC playback volume by a specified percentage, using positive values to raise volume and negative values to lower it.

Instructions

Increase or decrease the volume by a specified percentage.

Args: change: An integer representing the percentage to change the volume by. Positive values increase volume, negative values decrease 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": {
      "change": "<change>"
    },
    "name": "adjust_volume"
  }
}

Input Schema

Name	Required	Description	Default
`change`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 12, 2026

TDQS

B3.4/5.0

Behavior3/5

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

No annotations are supplied, so the description carries the full behavioral burden. It discloses the mutation semantics and direction convention (positive/negative), but leaves open whether the percentage is relative to the current level, what happens at the 0/100 bounds, and whether an out-of-range change errors or clamps.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The behavior is front-loaded in the first sentence with the parameter detail following in an Args block. Slightly verbose framing of the parameter as both 'integer' and 'percentage' but no wasted sentences.

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?

An output schema exists, so return values need no explanation, and there is only one parameter. The remaining gap is the relative-vs-absolute meaning of 'change' and boundary behavior, which for a mutation tool with zero annotations is a meaningful omission.

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?

Schema description coverage is 0% and the schema only labels the field 'change', so the description does real work by explaining that positive values increase and negative values decrease volume. It still doesn't clarify whether the integer is a percentage of the current volume or percentage points, which matters for correct invocation.

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?

States a specific verb and resource ('increase or decrease the volume') plus the unit of change ('specified percentage'), which distinguishes it from an absolute setter like set_volume without naming it. An agent can tell what the tool does at a glance.

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?

Usage is only implied: a relative percentage change suggests this is for nudging volume up/down rather than setting an absolute level, so an agent can infer it should prefer set_volume for a known target value. However, no sibling is named and no explicit when-to-use or when-not-to-use condition is given.

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