apc-mcp — Audio Plugin Coder MCP Server

apc-mcp is a Model Context Protocol server that brings audio plugin development workflows into any MCP-compatible client (Claude Code, OpenCode, VS Code with MCP, etc.).

It wraps CMake, ctest, clang-format, pluginval, and clap-validator into a clean tool interface for building, testing, linting, validating, and scaffolding JUCE, CLAP, VST3, and ARA plugin projects.

Tools

Related MCP server: REAPER MCP Server

Quick Start

Prerequisites

• Node.js 18+

• CMake 3.22+ — for build/configure tools

• clang-format — for lint tool (optional)

• pluginval (optional) — for VST3 validation

• clap-validator (optional) — for CLAP validation

• A JUCE/CLAP/VST3 audio plugin project with a plugins/ directory

Installation

{
  "mcp": {
    "apc-mcp": {
      "type": "local",
      "command": ["npx", "-y", "@scottmills306/apc-mcp"],
      "enabled": true
    }
  }
}

Or clone locally:

git clone https://github.com/scottmills306/apc-mcp.git
cd apc-mcp
npm install
# then point config to: node /path/to/apc-mcp/index.js

Project Config

Drop an apc-mcp.json in your project root to set per-project defaults:

{
  "generator": "Ninja",
  "config": "Release",
  "buildDir": "build",
  "pluginsDir": "plugins",
  "validateFormats": ["VST3", "CLAP"],
  "validateCommand": "pluginval",
  "clapValidatorCommand": "clap-validator"
}

When this file is present, projectPath is optional in tool calls — the server auto-detects your project from the working directory.

Usage Examples

Build

audio_plugin_build()
audio_plugin_build(config="Release", clean=true)
audio_plugin_build(projectPath="/path/to/other-plugin", target="MyPlugin_Standalone")

Build output includes parsed error/warning counts.

Configure

audio_plugin_configure(generator="Ninja")
audio_plugin_configure(options="-DAPC_ENABLE_VISAGE=ON")

Test

audio_plugin_test()
audio_plugin_test(config="Release", testName="MyPluginTest")

Lint

audio_plugin_lint()
audio_plugin_lint(fix=true)
audio_plugin_lint(target="plugins/Foo/Source")

List plugins

audio_plugin_plugins(format="json")

Returns structured JSON when format="json", or human-readable text by default.

Validate built binaries

audio_plugin_validate()
audio_plugin_validate(format="VST3")
audio_plugin_validate(format="CLAP")

Scans the build directory for plugin binaries and runs the appropriate validator on each.

Scaffold a new plugin

audio_plugin_create(name="Phaser9000", type="clap")
audio_plugin_create(name="MyVerb", type="juce", vendor="MyCompany", formats="VST3;AU")
audio_plugin_create(name="SimpleDelay", type="clap", vendor="MyCompany", description="A simple delay effect")

Creates a working plugin stub with CMakeLists.txt, source files, and proper CLAP or JUCE structure.

Project Structure

my-plugin/
├── apc-mcp.json              # Per-project config (optional)
├── CMakeLists.txt            # Root CMake project
├── plugins/
│   ├── MyPlugin/
│   │   ├── CMakeLists.txt    # Per-plugin CMake
│   │   ├── Source/
│   │   └── status.json       # Optional metadata
│   └── ...
├── common/                   # Shared sources (optional)
└── build/                    # Build directory (auto-created)

Development

git clone https://github.com/scottmills306/apc-mcp.git
cd apc-mcp
npm install
npm test

Tests use Node's built-in node:test runner — zero test dependencies.

Why apc-mcp?

• Project-agnostic — works with any audio plugin repo, no hardcoded paths

• Configurable — drop apc-mcp.json for per-project defaults, or pass everything explicitly

• Structured output — tools return parsed error/warning counts, pass/fail summaries, and optional JSON

• Plugin scaffolding — audio_plugin_create generates working CLAP and JUCE stubs from templates

• Validation — runs pluginval and clap-validator on your built binaries

• Leverages your existing toolchain — wraps cmake, ctest, clang-format instead of reinventing them

• MIT licensed

Publishing to npm

The CI/CD pipeline publishes to npm automatically when a v* tag is pushed:

git tag v1.0.1 && git push origin v1.0.1

Requires NPM_TOKEN secret on the repository.

License

MIT © 2026 Scott Mills