PostFader V12 — FL Studio MCP Server

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pattern_set

Destructive

Rename, recolor, resize, or select an existing FL Studio pattern in one call by setting only the fields you need changed. Requires write mode; writes verify individually and are non-atomic.

Instructions

Rename, recolor, resize, or select one existing pattern in one call.

Set only the fields to change. Requires write mode. Writes run in the order
name/color, length, then selection, each read back on a later tick with its
own receipt; verified is true only when all verified. Non-atomic. Use
pattern_create for a new empty pattern. Does not save the project.

Input Schema

TableJSON Schema

Name	Required	Description
`name`	No	Absolute pattern name.
`color`	No	Absolute unsigned FL color word.
`select`	No	Also make this FL's current pattern, after the other changes.
`length_beats`	No	Absolute pattern length in beats.
`pattern_number`	Yes	One-based pattern number.
`expected_before`	No	Optional current values from pattern_list for the fields this call changes; refuse if any changed.
`stop_on_unverified`	No	Skip the remaining writes after the first write whose readback did not verify. An unknown outcome always stops the sequence.
`session_fingerprint`	No	Optional session_fingerprint from a recent read. The call refuses after a bridge reload or a reported project load. This is a concurrency guard, not authentication or a durable project identity.

Output Schema

TableJSON Schema

Name	Required	Default
`results`	Yes
`verified`	Yes
`warnings`	No
`completed`	Yes
`applied_at`	Yes
`project_saved`	No
`skipped_count`	Yes
`skipped_steps`	No
`pattern_number`	Yes
`schema_version`	No	1.0
`stopped_reason`	No
`attempted_count`	Yes
`requested_count`	Yes
`rollback_attempted`	No
`stop_on_unverified`	Yes
`session_fingerprint`	Yes
`automatic_replay_attempted`	No
`one_session_preflight_completed`	No

Schema Changelog

Changes observed during successful MCP inspections.

Addedv11.0.2Oct 5, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Annotations already flag destructive/openWorld/non-idempotent, and the description adds substantial non-obvious behavior: the fixed write order (name/color, length, selection), per-write readback on a later tick with individual receipts, the meaning of 'verified', non-atomicity, and that it does not save the project. This is exactly the kind of context annotations cannot convey.

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 purpose is front-loaded in one line, followed by tightly packed clauses covering mode, sequencing, verification, atomicity, the sibling alternative, and persistence. Every sentence carries information with no filler.

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?

With an output schema present, return-value explanation is not needed, and the description still covers the write-mode requirement, non-atomicity, the verified flag's semantics, and persistence behavior. For a destructive multi-field mutation, nothing an agent needs to call it correctly is missing.

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 100%, so the baseline is 3, but the description adds param-relevant semantics: that only changed fields should be supplied and the ordering in which the changed fields are applied. It does not add further format detail, but it meaningfully frames how the parameters interact.

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 first sentence names specific verbs (rename, recolor, resize, select), the resource (one existing pattern), and the scope (one call), and explicitly distinguishes itself from pattern_create. An agent can tell it apart from sibling tools without opening any schema.

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?

It states the operational precondition ('Requires write mode'), the editing convention ('Set only the fields to change'), and routes to the alternative ('Use pattern_create for a new empty pattern'). It lacks explicit when-not conditions for other mutating siblings, so it stops just 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.

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