mastering

Compare presets on 24 seconds

preview_styles

Master the middle 24 s of the track in 2-6 presets at once and get each one's loudness plus a listen link. FREE (6 per day). Use this instead of guessing a preset, and instead of spending a credit to 'try' one.

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": {
      "audio_url": "<audio_url>"
    },
    "name": "preview_styles"
  }
}

Input Schema

Name	Required	Description	Default
`styles`	No	Preset keys from list_presets. Default: edm, pop, rnb, standard.
`audio_url`	Yes	Public https URL of the audio file (wav/mp3/flac/m4a). A share link to the page works too — Suno/Udio song pages, Google Drive and Dropbox links are resolved to the file automatically.

Output Schema

Name	Required	Description	Default
`job_id`	No
`styles`	No
`poll_with`	No
`preview_url_template`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 13, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations only declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the description carries real added weight: it discloses cost (FREE), a rate limit (6 per day), and what the preview actually renders (middle 24 s across 2-6 presets). It does not explain whether the call is synchronous or returns a job to poll, which is a gap given the presence of a get_job sibling.

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?

Two short sentences, front-loaded with the action and scope, with the cost/quota parenthetical and the anti-pattern guidance packed in without waste.

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 no explanation, and the description covers cost, quota, scope and selection guidance. The only notable omission is the async/job semantics of the call, which matters for a tool family that includes get_job.

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 100% and both parameters are already documented in the schema, including the preset default and the accepted URL forms. The description's '2-6 presets' merely restates the minItems/maxItems bounds, so baseline 3 is appropriate.

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?

States a specific verb (master), a precisely scoped resource (the middle 24 s of the track), a count range (2-6 presets at once), and the outputs (per-preset loudness plus a listen link). An agent can immediately tell this apart from a full-length mastering sibling because the preview window and multi-preset compare are explicit.

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?

Gives a clear when-to-use rule: 'Use this instead of guessing a preset, and instead of spending a credit to try one,' which implicitly positions it against the paid mastering tools. It stops short of naming master_track/batch_master directly as the alternative, so the routing is clear but slightly inferential.

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

All mastering tools Inspect

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