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mcp_opendaw_apply_contour

Apply a melodic contour to redistribute pitch patterns (ascending, descending, arch, wave) while preserving note timing and duration.

Instructions

Apply a melodic contour shape to existing notes.

Redistributes note pitches to follow a specified contour profile while keeping timing and duration unchanged. Unlike transpose_notes (uniform shift), this reshapes the melody direction — ascending, descending, arch, inverted arch, wave, or custom.

The tool calculates a target pitch for each note based on its position in the sequence (0..1 normalized) mapped through the contour function, then snaps to the nearest scale degree if requested. The original pitch range center is preserved.

Contours:

  • "ascending": low to high across the phrase

  • "descending": high to low

  • "arch": rise then fall (peak at midpoint)

  • "inverted_arch": fall then rise (valley at midpoint)

  • "wave": sinusoidal up-down-up

  • "escalating": stepwise ascending with plateaus

Args: unit_index: Audio unit index track_index: Note track index region_index: Region index (-1 = first region) contour: Contour shape name range_semitones: Pitch range span in semitones (1-48, default 12=octave) snap_to_scale: Scale for snapping results (""=chromatic, "major", "minor", "dorian", "phrygian", "lydian", "mixolydian", "locrian", "harmonic_minor", "melodic_minor", "pentatonic", "blues") root: Root note for scale snapping preserve_first: Keep first note pitch unchanged preserve_last: Keep last note pitch unchanged

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
rootNoC
contourNoarch
unit_indexYes
track_indexYes
region_indexNo
preserve_lastNo
snap_to_scaleNo
preserve_firstNo
range_semitonesNo

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes
Behavior4/5

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

No annotations exist; the description discloses that pitches are redistributed, timing and duration unchanged, snap-to-scale option, and preservation of original pitch range center. It does not mention return values or potential side effects beyond modification.

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?

Well-structured: starts with one-sentence summary, then explanatory paragraph, lists contour shapes, then parameter descriptions. Efficient with no wasted words.

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?

Covers core functionality and parameters well. Does not describe return values or error conditions, but the presence of an output schema reduces the need. Overall adequate for a transformation tool.

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?

With 0% schema coverage, the description adds extensive meaning: explains all parameters (unit_index, track_index, region_index, contour, range_semitones with range, snap_to_scale with options, root, preserve_first/last). This fully compensates for the schema's lack of descriptions.

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 applies a melodic contour shape to existing notes, contrasting with transpose_notes. It provides specific verb and resource, and distinguishes from sibling tools by explaining the difference.

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 explicitly contrasts with transpose_notes, providing an alternative. It implies when to use this tool (reshaping melody) vs uniform shift, but lacks explicit 'when not to use' guidance.

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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