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LiveSession MCP

LiveSession MCP

by Uri-Rosen
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Local

write_chords

Destructive

Generate chord progressions from symbols into Session clips, auto-creating empty clips and applying configurable voicing, pattern, and voice-leading options.

Instructions

Write a chord progression by symbol into a Session clip (created if empty), with smooth voice leading.

  • chords: ["Am7", "Fmaj7", "C/E", "G7sus4"] — also add9, m7b5, dim7, 6/9, 9, 11, 13...

  • style: close, open, spread (two-hand piano), drop2, shell, power

  • pattern: block, half, arp_up, arp_down, arp_updown, broken, pulse8

  • center: MIDI note the voicing sits around (60 = middle C)

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "track_index": "<track_index>",
      "clip_index": "<clip_index>",
      "chords": "<chords>"
    },
    "name": "write_chords"
  }
}

Input Schema

NameRequiredDescriptionDefault
styleNoclose
centerNo
chordsYes
patternNoblock
replaceNo
add_bassNo
humanizeNo
velocityNo
clip_indexYes
track_indexYes
beats_per_chordNo

Output Schema

NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv2.0.0

TDQS

B3.1/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the agent knows this mutates and may destroy content. The description adds useful non-annotation detail: the target is a Session clip, one is created if empty, and voicings use smooth voice leading. However it never states that existing notes are overwritten when replace defaults to true, which is exactly the destructive behavior an agent needs spelled out.

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?

Front-loaded with the action and scoping clause, then a tight bullet list where each bullet maps to one parameter with examples. Slight inefficiency: the bullet list reads like schema documentation rather than routing guidance, and the trailing ellipsis after the chord list is imprecise.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An 11-parameter mutation tool with zero schema descriptions and destructiveHint=true needs more than four documented parameters. Missing are the overwrite semantics of replace, the effect of add_bass/humanize/velocity/beats_per_chord, and any differentiation from the several sibling progression/chord tools; only the output side is covered by the output schema.

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 0%, so the description carries the burden; it does well on four parameters by giving concrete value lists and an example for chords, style, pattern, and center (60 = middle C). But seven parameters are entirely undocumented, notably replace (default true, which drives the destructive behavior), add_bass, humanize, velocity, beats_per_chord, and the required track_index/clip_index targeting.

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 ('Write a chord progression by symbol into a Session clip') plus two notable behaviors (auto-create if empty, smooth voice leading). It implicitly separates itself from arrangement-writing siblings via 'Session clip', but never names write_progression, write_named_progression, or chord_info, which are the closest alternatives.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

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

There is no when-to-use / when-not-to-use guidance and no mention of alternatives such as write_progression, write_named_progression, generate_melody, or chord_info. The only contextual hint is the parenthetical that the clip is created if empty, which describes mechanics rather than tool selection.

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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