PostFader V12 — FL Studio MCP Server

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run_stop

Stops an active production run so no further operations execute. Completed changes remain in the FL Studio project, and the final state plus receipts are returned.

Instructions

Stop a run so no further operations execute.

Completed changes stay in the project; nothing is undone (use
project_step_history to undo). Returns the run's final state and
receipts.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`run_id`	Yes	Production Run identifier from run_execute or run_list.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`run_id`	Yes
`status`	Yes
`summary`	Yes
`blockers`	No
`receipts`	No
`warnings`	No
`phase_plan`	No
`run_context`	No
`project_saved`	No
`timing_report`	No
`attempted_count`	Yes
`completed_count`	Yes
`creation_outcome`	No
`readiness_report`	No
`total_operations`	Yes
`generated_outputs`	No
`write_mode_active`	No
`rollback_attempted`	No
`session_fingerprint`	No
`project_state_digest`	No
`write_mode_enable_count`	No
`write_mode_disable_count`	No
`write_mode_shutdown_verified`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv12.0.3Oct 5, 2026
- changedOutput schema / $defs / ProcessingPlan / properties / missing_capabilities / maxItems
```
Previous value: -128New value: +256
```
Addedv11.0.2Oct 5, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations declare non-destructive/read-only=false, but the description adds real behavioral value: completed changes persist and 'nothing is undone,' which clarifies the partial-completion semantics. With output schema handling returns, this is strong but doesn't cover idempotency (annotated false) or re-invocation behavior.

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 core action and immediately followed by the key side-effect clarification and the undo alternative. No wasted phrasing.

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?

Given annotations, a fully documented single parameter, and an existing output schema, the description covers the essential behavioral nuance (nothing is undone). Only minor gaps remain, such as what happens if the run is already stopped.

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% with a single required run_id, so the schema already documents the parameter fully. The description adds no syntax or format detail beyond what the schema provides, making the baseline 3 correct.

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 (stop) and resource (a run), plus scope: 'so no further operations execute.' An agent can distinguish it from run_execute, run_continue, and run_get 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 Guidelines4/5

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

Names the alternative for the undo use case explicitly ('use project_step_history to undo'), routing the agent correctly. It does not state a when-not-to-use condition (e.g., stopping an already-finished run), so it falls 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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