dosbox-mcp

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mixer_channel_volume

Set a DOSBox mixer channel's left and right volume by name, such as SB, GUS, or CDAUDIO, to adjust audio balance for emulated DOS programs.

Instructions

Set a mixer channel's user volume by name (SB, GUS, CDAUDIO, SPKR, etc.).

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": {
      "channel": "<channel>",
      "left": "<left>",
      "right": "<right>"
    },
    "name": "mixer_channel_volume"
  }
}

Input Schema

Name	Required	Description
`left`	Yes	Left volume (0.0+)
`right`	Yes	Right volume (0.0+)
`channel`	Yes	Channel name

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.2.1Oct 16, 2026

TDQS

B3.4/5.0

Behavior3/5

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

The readOnlyHint=false annotation aligns with the mutating verb 'Set', so there is no contradiction. The description adds the useful nuance that it is 'user volume' on a named channel, but it says nothing about persistence, clamping of out-of-range values, or whether the change is reversible.

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?

A single front-loaded sentence with the verb first and the parenthetical examples doing useful work. Nothing is wasted or buried.

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 simple three-parameter setter with no output schema, the description is adequate on the target channel but leaves the volume scale semantics (linear 0.0+, dB, or percent) and return behavior unstated. Annotations are minimal, so more behavioral detail would have helped.

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 already 100%, so the baseline is 3, but the description's concrete channel-name examples (SB, GUS, CDAUDIO, SPKR) give enum-like guidance the generic 'Channel name' schema field lacks. The left/right parameters get no added meaning beyond the schema's '0.0+' ranges.

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 ('Set') and resource ('a mixer channel's user volume'), and the channel-name examples (SB, GUS, CDAUDIO, SPKR) make the target concrete. It does not explicitly distinguish itself from the sibling mixer_volume (likely master volume), so it stops short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no when-to-use guidance and no mention of the alternatives (mixer_volume, mixer_mute, mixer_unmute, mixer_status). The agent must infer that this is the per-channel variant rather than the master-volume tool.

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