PostFader V12 — FL Studio MCP Server

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mixer_list_tracks

Read-onlyIdempotent

List all FL Studio mixer tracks with names, levels, mute/solo state, and loaded effects. Use it to find track indices and effect slots before routing or plugin edits.

Instructions

List mixer tracks with names, levels, mute/solo state, and loaded effects.

Read-only. Index 0 is Master. Use it to find track indices and effect slots
before mixer_set_track or plugin tools; use mixer_get_track for one track's
built-in EQ and outgoing sends, and mixer_start_peak_watch for levels over
time.

Input Schema

TableJSON Schema

Name	Required	Description
`only_used`	No	Apply a conservative used-track heuristic. False, the default, lists every track.
`max_tracks`	No	Optional early page limit for a large mixer.
`include_peaks`	No	Include instantaneous meter values; these are not audio analysis.

Output Schema

TableJSON Schema

Name	Required	Default
`tracks`	Yes
`partial`	No
`warnings`	No
`only_used`	Yes
`observed_at`	Yes
`schema_version`	No	1.0
`total_track_count`	Yes
`observation_atomic`	No
`project_dirty_flag`	No
`scanned_track_count`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Addedv11.0.2Oct 5, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already declare readOnly/idempotent/non-destructive, so the 'Read-only' line is largely redundant, but 'Index 0 is Master' is genuinely useful behavioral context the annotations don't convey. It stops short of describing ordering or pagination behavior, keeping it from a 5.

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 tight sentences, front-loaded with the returned content and follow-up routing. No filler; every clause either describes output or routes to a sibling tool.

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?

An output schema exists, so return format needn't be explained, and the annotations cover the safety profile. Between the description, schema, and output schema, an agent has everything needed to call this correctly.

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%, so only_used, max_tracks, and include_peaks are already documented in the schema. The description adds no semantics beyond that, which is the correct baseline 3 when the schema carries the burden.

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 and resource (list mixer tracks) and enumerates the returned fields: names, levels, mute/solo state, and loaded effects. It explicitly distinguishes itself from mixer_get_track and mixer_start_peak_watch, so an agent can choose correctly without opening schemas.

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

Usage Guidelines5/5

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

Gives explicit routing: use this to find track indices and effect slots before mixer_set_track or plugin tools; use mixer_get_track for a single track's EQ and sends; use mixer_start_peak_watch for levels over time. When-to-use and named alternatives are both present.

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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