kinocut

Overview Schema Source Related Servers Discussions Admin

video_duck_audio

Mix background music under a video's dialogue with automatic ducking driven by the existing audio, so music dips during speech and recovers in pauses for shorts, reels, and podcast clips.

Instructions

Mix background music under a video's voice with automatic ducking.

The video's own audio (voice/dialog) drives FFmpeg's sidechain compressor, so the music dips while speech plays and recovers in pauses — the standard treatment for shorts, reels, and podcast clips.

Args: input_path: Video whose existing audio drives the ducking. music_path: Background music or ambience to mix underneath. output_path: Where to save the result. Auto-generated if omitted. music_volume: Base music level before ducking (0-2, default 0.6). threshold: Sidechain level above which ducking engages (0-1). ratio: Compression ratio applied while voice plays (1-20). attack: How fast the music dips, in milliseconds (1-2000). release: How fast the music recovers, in milliseconds (1-9000).

Input Schema

Name	Required	Description
`ratio`	No
`attack`	No
`release`	No
`overwrite`	No	Explicitly allow replacing existing media. Existing non-media files are protected.
`threshold`	No
`input_path`	Yes
`music_path`	Yes
`output_path`	No
`music_volume`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv1.16.4Oct 24, 2026

addedInput schema / properties / overwrite

Added value: +{
+  "default": false,
+  "description": "Explicitly allow replacing existing media. Existing non-media files are protected.",
+  "title": "Overwrite",
+  "type": "boolean"
+}

Changed1 schema field changedv1.16.0Oct 3, 2026
- addedInput schema / additionalProperties
```
Added value: +false
```
Addedv1.6.0Jul 10, 2026

TDQS

A3.6/5.0

Behavior3/5

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

No annotations are provided, so the description carries full behavioral burden. It helpfully explains the sidechain-compressor mechanism and the dip/recover behavior, but omits what happens if the input video lacks an audio track, whether the existing audio is preserved or replaced, and error/overwrite behavior beyond the bare schema entry.

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?

Purpose is front-loaded in one sentence, followed by a compact explanation of the mechanism, then a structured Args list. The Args list repeats parameter names already in the schema but earns most of its space given the low schema coverage; no egregious padding.

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?

Output schema exists so return values needn't be described. For a no-annotation mutation tool, the description covers the core mechanism and nearly all parameters, leaving mainly edge-case behavior (missing voice track, audio replacement) unaddressed.

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 only 11%, but the Args block documents 8 of 9 parameters in plain language with ranges and most defaults ('Base music level before ducking (0-2, default 0.6)'), adding real meaning beyond bare titles. Only 'overwrite' is left to the schema description, which does cover it.

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 specific verb and resource: 'Mix background music under a video's voice with automatic ducking.' The ducking mechanism implicitly distinguishes it from plain-mix siblings like video_mix_audio and video_add_audio, though no sibling is named explicitly.

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?

Describes the target use case ('standard treatment for shorts, reels, and podcast clips') but gives no explicit when-to-use-vs-alternative guidance and no exclusions relative to video_mix_audio / video_add_audio / video_audio_bed. Usage is implied rather than directed.

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

Deploy Server