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mcp_opendaw_add_passing_tones

Smooth melodic leaps by adding diatonic passing tones between notes with intervals larger than a second. Works with various scales and directional options.

Instructions

Add passing tones between existing notes for smoother melodic lines.

Inserting diatonic passing tones in gaps where consecutive notes have an interval larger than a 2nd. The passing tone is placed on the weak part of the beat, connecting the two notes stepwise through the scale.

This is a fundamental counterpoint technique — makes large melodic leaps sound smoother by filling them with scale steps. Bach inventions, jazz walking lines, and pop vocal melismas all use passing tones.

Passing tones are only added when:

  • The interval between consecutive notes is > 2 semitones

  • There is enough time gap between notes (at least 1/8 note)

  • The interval does not exceed max_interval semitones

Args: unit_index: Audio unit index track_index: Note track index region_index: Region index (-1 = first region) scale: Scale for diatonic passing tones ("major", "minor", "dorian", "phrygian", "lydian", "mixolydian", "locrian", "harmonic_minor", "melodic_minor", "pentatonic", "blues", "chromatic") root: Root note for scale (C, C#, D, ... B) max_interval: Maximum interval (semitones) to fill with passing tones (3-12, default 7 = perfect 5th). Intervals larger than this are left as leaps. velocity: Velocity of passing tones (0-1, default 0.6 — slightly quieter than melodic notes, as is traditional) duration_fraction: Duration of passing tones as fraction of the gap between notes (0.25-1.0, default 0.5) direction: Passing tone direction — "auto": choose direction that fits scale better "ascending": always step up from lower to higher note "descending": always step down from higher to lower note "nearest": use nearest scale tone to midpoint cross_track: If >= 0, place passing tones on this track index instead of source track (preserves original melody)

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
rootNoC
scaleNomajor
velocityNo
directionNoauto
unit_indexYes
cross_trackNo
track_indexYes
max_intervalNo
region_indexNo
duration_fractionNo

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes
Behavior4/5

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

No annotations are provided, so the description carries full burden. It thoroughly explains the behavior: inserts diatonic passing tones on weak beats, stepwise, respecting scale and duration. It mentions cross_track to preserve original melody, but could clarify if this is additive or modifies existing notes.

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?

The description is well-structured with sections, but is somewhat lengthy. However, every sentence contributes value, and the parameter list is clear.

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?

Given the complexity (10 parameters, no annotations, output schema present), the description covers the operation, conditions, and parameters completely. No gaps remain for the agent to infer.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must fully explain parameters. It does: each parameter (unit_index, track_index, region_index, scale, root, max_interval, velocity, duration_fraction, direction, cross_track) is described with defaults, ranges, and meanings.

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 description clearly states the tool adds passing tones to smooth melodic lines, specifies it's a counterpoint technique, and distinguishes it from similar tools by focusing on stepwise filling of large intervals.

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?

The description provides explicit conditions for when passing tones are added (interval > 2 semitones, time gap >= 1/8 note, interval <= max_interval), but does not explicitly mention alternative tools like neighbor tones or anticipations.

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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