vlc-mcp

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set_equalizer

Adjust VLC equalizer settings by enabling or disabling it, applying a preset, changing preamp level, or setting gain for a specific frequency band; only supplied arguments are updated.

Instructions

Change the equalizer. Only the arguments you pass are applied.

Args: enabled: True to enable, False to disable the equalizer preset_id: Preset id from get_equalizer preamp_db: Preamp level, -20 to 20 dB band: Band 0-9 (0: 60 Hz, 1: 170 Hz, 2: 310 Hz, 3: 600 Hz, 4: 1 kHz, 5: 3 kHz, 6: 6 kHz, 7: 12 kHz, 8: 14 kHz, 9: 16 kHz). Requires gain_db. gain_db: Gain for the band, -20 to 20 dB

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "set_equalizer"
  }
}

Input Schema

Name	Required	Description	Default
`band`	No
`enabled`	No
`gain_db`	No
`preamp_db`	No
`preset_id`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 12, 2026

TDQS

A3.8/5.0

Behavior3/5

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

No annotations exist, so the description carries the full behavioral burden. It does disclose the partial-update semantics and numeric ranges, but leaves the interaction between preset_id and band/gain unexplained, along with persistence and whether any settings are reset.

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 docstring Args format is front-loaded with the behavioral rule before the parameter list, and each line adds real information. The frequency table for bands is long but earns its space by removing guesswork.

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

Completeness4/5

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 not be explained, and the parameter documentation is thorough. The only notable gap for a no-annotation mutation tool is the precedence between preset_id and per-band gain_db.

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

Parameters5/5

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

With 0% schema description coverage across 5 parameters, the description fully compensates: it defines units and ranges for preamp_db and gain_db, maps all ten band indices to frequencies, states the band-requires-gain_db dependency, and identifies where preset_id comes from. All five parameters gain meaning beyond the bare title-cased schema properties.

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 opens with a specific verb+resource ("Change the equalizer") and immediately clarifies the partial-update scope. It points at the counterpart reader ("Preset id from get_equalizer"), so the agent can place it relative to that sibling without opening a schema.

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?

"Only the arguments you pass are applied" is genuinely useful usage context for a partial-update tool, and the preset_id reference implies reading via get_equalizer first. However, there is no explicit statement of when to prefer a preset over per-band gain, or what happens if both are supplied, so guidance is implied rather than stated.

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