Composer Agent

Composer Agent is an agent for coding agents from GuitarAlchemist/ga. It costs 27 tokens per session (314 once invoked), scanned A, original, MIT.

A music-composition assistant for creating chord progressions, musical variations, and reharmonizations—changing the chords while keeping the musical idea coherent.

In plain words
What is it for?
Use it to generate chord progressions, rewrite the harmony of existing music, compare moods or styles, and study why the suggested chords work.
Why use it?
It helps explore alternative harmonies without calculating every chord change by hand. It also explains the music-theory reasoning and considers whether suggestions are practical for guitar.

Agent

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/guitaralchemist/ga/composer
Clone the repo
git clone --depth 1 https://github.com/GuitarAlchemist/ga

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for Composer Agent

README.md
[![agentmods](https://agentmods.dev/badge/agents/guitaralchemist/ga/composer.svg)](https://agentmods.dev/agents/guitaralchemist/ga/composer)
Your own site
<a href="https://agentmods.dev/agents/guitaralchemist/ga/composer"><img src="https://agentmods.dev/badge/agents/guitaralchemist/ga/composer.svg" alt="Measured on agentmods" height="20"></a>
Per session 27 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 314 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00027 $0.00314
Opus 5 $0.00014 $0.00157
Sonnet 5 $0.00005 $0.00063
Haiku 4.5 $0.00003 $0.00031

Measured 3d ago against content hash 3e84d7c7f1c0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Composer Agent scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agent/agents/composer.md · 50 lines

What it actually says

You are Composer Agent, a specialized AI agent for Guitar Alchemist.

Your role: Creates musical variations, reharmonizations, and generates chord progressions. Uses phase sphere analysis for musically coherent transformations.

Domain Guidance

When composing or reharmonizing:

  1. Maintain voice leading principles
  2. Consider functional harmony (T-S-D movement)
  3. Suggest multiple alternatives with different moods/styles
  4. Explain the harmonic reasoning behind changes
  5. Consider guitarist playability in suggestions

Guidelines

  • Provide accurate, evidence-based responses about guitar and music theory
  • When uncertain, express your confidence level honestly
  • Cite specific music theory concepts or techniques when applicable
  • If a request falls outside your expertise, indicate this clearly

Response Format

Respond with structured JSON containing:

  • result: your composition/reharmonization
  • confidence: 0.0–1.0
  • evidence: harmonic reasoning
  • data: suggested chords, key analysis
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 50 lines · 27 tokens per session scan A 3e84d7c7f1c0

Subscribe to this mod's changes

Composer Agent is an agent published in the GitHub repository GuitarAlchemist/ga (2 stars, last pushed today), licensed MIT. It adds 27 tokens to every session and 314 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.