X32/M32 MCP Server

Set Bus Fader Volume

bus_set_volume

Idempotent

Set the fader level for any mix bus on a Behringer X32/M32 mixer, using linear or dB values for precise volume control.

Instructions

Set the fader level (volume) for a specific mix bus on the X32/M32 mixer. Supports both linear values (0.0-1.0) and decibel values (-90 to +10 dB). Unity gain is 0 dB or 0.75 linear.

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": {
      "bus": "<bus>",
      "value": "<value>"
    },
    "name": "bus_set_volume"
  }
}

Input Schema

Name	Required	Description	Default
`bus`	Yes	Mix bus number from 1 to 16
`unit`	No	Unit of the value: "linear" (0.0-1.0) or "db" (-90 to +10 dB). Default is "linear".	linear
`value`	Yes	Volume value (interpretation depends on unit parameter)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv3.2.0Aug 9, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already indicate a non-read-only, idempotent, and non-destructive operation. The description adds useful context by disclosing the accepted value ranges for both linear and dB units and defining unity gain, which goes beyond the annotations without contradiction.

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 sentences, with the first sentence immediately stating the core purpose and the second providing key unit details. There is no redundancy or filler, making it highly efficient and front-loaded.

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?

Given the simple three-parameter interface, high schema coverage, and helpful annotations, the description covers all essential information an agent needs to invoke the tool correctly. No output schema is required, and the description fully compensates for any potential ambiguity around value interpretation.

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?

The schema covers all parameters with descriptions (100% coverage), which sets a baseline of 3. The description adds extra value by specifying the numeric ranges for linear (0.0-1.0) and dB (-90 to +10 dB) values and the unity gain mapping, enriching parameter understanding beyond the schema alone.

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 clearly states the action ('Set the fader level') and the target resource ('a specific mix bus on the X32/M32 mixer'), distinguishing it from sibling tools like channel_set_volume and main_set_volume. It also provides specific unit details, making the purpose unambiguous.

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 gives clear context by specifying the tool is for mix buses and describes the supported unit types, implying when it should be used. However, it does not explicitly mention alternative tools or exclusion conditions, so it falls 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.