Gizmos Audacity MCP

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Contrast

audacity_contrast

Measure RMS level differences between foreground speech and background room tone to check numeric audio contrast, with track controls and selection restored for each range.

Instructions

Measure the RMS level difference between foreground speech and background room tone without opening Audacity Contrast. Each range is exported with current track controls and selection restored. This is a numeric contrast check, not full accessibility certification.

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": {
      "foreground": "<foreground>",
      "background": "<background>"
    },
    "name": "audacity_contrast"
  }
}

Input Schema

Name	Required	Description	Default
`minimumDb`	No
`background`	Yes
`foreground`	Yes

Output Schema

Name	Required	Description	Default
`reason`	No
`status`	Yes
`minimumDb`	Yes
`differenceDb`	Yes
`backgroundRmsDbfs`	Yes
`foregroundRmsDbfs`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 10, 2026

TDQS

B3.2/5.0

Behavior3/5

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

Adds real context beyond the annotations: ranges are exported and track controls/selection are restored afterward, which explains the non-readOnly, non-idempotent flags. It still omits where exports land, what happens on a failed range, and the pass/fail semantics of the measurement.

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?

Three short sentences with the core action front-loaded and the scope disclaimer last. No filler, though the middle sentence about export/restore could be tightened.

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 needn't be described, but for a tool with nested range objects and a threshold parameter, the definition leaves minimumDb undefined and says nothing about export destinations or threshold behavior, which are central to invoking it correctly.

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

Parameters2/5

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

Schema description coverage is 0% and the description explains none of the three parameters — in particular minimumDb (default 20) is never mentioned, nor are the time units or track identifier format for the nested foreground/background objects. The description does not compensate for the coverage gap.

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 concrete verb and resource: 'Measure the RMS level difference between foreground speech and background room tone.' The 'without opening Audacity Contrast' clause pins it to a specific workflow, though it never contrasts itself with the nearby audacity_measure sibling.

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?

Implies usage (numeric contrast check, not accessibility certification) and signals it replaces the manual Contrast dialog. It gives no explicit when-to-use vs. audacity_measure or audacity_loudness_target, and no prerequisites such as needing foreground/background selections to exist first.

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

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