---
license: mit
library_name: hct-spec
tags:
  - multi-agent
  - coordination
  - agent-orchestration
  - llm-agents
  - mcp
  - a2a
---

# Harmonic Coordination Theory (HCT) - Specification

**The canonical specification for HCT coordination signals and performance parameters.**

## Overview

Harmonic Coordination Theory (HCT) proposes a musical ontology for multi-agent coordination. Current frameworks (LangGraph, CrewAI, AutoGen) give you orchestration tools but lack a shared language for **coordination semantics**—timing, quality, intent, and harmony.

HCT fills this gap using musical performance as the ontology: cues, fermatas, tempo, and dissonance become engineering primitives.

## The 7 Coordination Signals

| Signal | Meaning | Use Case | Musical Origin |
|--------|---------|----------|----------------|
| **CUE** | "Your turn—act now" | Task dispatch | Conductor's downbeat |
| **FERMATA** | "Hold for approval" | Human-in-the-loop | Sustained note |
| **ATTACCA** | "Immediate handoff" | Real-time flows | Seamless movement transition |
| **VAMP** | "Loop until ready" | Quality checks | Repeat until cue |
| **CAESURA** | "Full stop" | Emergency shutdown | Dramatic silence |
| **TACET** | "Stay silent" | Resource conservation | Instrument rests |
| **DOWNBEAT** | "Sync point" | Barrier synchronization | Unified entry |

## Quick Start

### Python
```python
from hct_mcp_signals import cue, fermata

# Signal the analyst to start with high urgency
signal = cue("orchestrator", ["analyst"], urgency=9, tempo="presto")

# Hold for human approval before publishing
hold = fermata("report_agent", "Ready for compliance review", hold_type="human")
```

### TypeScript
```typescript
import { cue, fermata } from '@hct-mcp/signals';

const signal = cue("orchestrator", ["analyst"], { urgency: 9, tempo: "presto" });
const hold = fermata("report_agent", "Ready for review", { holdType: "human" });
```

### Rust
```rust
use hct_mcp_signals::{cue, fermata, Urgency};

let signal = cue("orchestrator", &["analyst"], Urgency::Nine, Tempo::Presto);
let hold = fermata("report_agent", "Ready for review", HoldType::Human);
```

### Go
```go
import "github.com/stefanwiest/hct-mcp-signals/go"

signal := cue.Cue("orchestrator", []string{"analyst"}, 9, "presto")
hold := fermata.Fermata("report_agent", "Ready for review", "human")
```

## Installation

```bash
# Python
pip install hct-mcp-signals

# Node.js
npm install @hct-mcp/signals

# Rust
cargo add hct-mcp-signals

# Go
go get github.com/stefanwiest/hct-mcp-signals/go
```

## Protocol Extensions

### HCT-MCP Signals
**For Anthropic MCP Protocol** — The coordination layer that MCP is missing.

[![PyPI](https://img.shields.io/pypi/v/hct-mcp-signals)](https://pypi.org/project/hct-mcp-signals/)
[![npm](https://img.shields.io/npm/v/@hct-mcp/signals)](https://www.npmjs.com/package/@hct-mcp/signals)
[![crates.io](https://img.shields.io/crates/v/hct-mcp-signals)](https://crates.io/crates/hct-mcp-signals)

→ [GitHub: stefanwiest/hct-mcp-signals](https://github.com/stefanwiest/hct-mcp-signals)

### HCT-A2A Extension
**For Google A2A Protocol** — Coordination semantics for decentralized agent meshes.

→ [GitHub: stefanwiest/hct-a2a](https://github.com/stefanwiest/hct-a2a)

## Research Papers

- [Harmonic Coordination Theory](https://www.stefanwiest.de/research) — CS.AI / CS.MA publications
- [The 97% Problem](https://seekingsota.com/p/the-97-problem) — Why multi-agent systems fail to scale

## Implementation

- **hct-core**: [github.com/stefanwiest/hct-core](https://github.com/stefanwiest/hct-core) — Reference implementation
- **hct-patterns**: [github.com/stefanwiest/hct-patterns](https://github.com/stefanwiest/hct-patterns) — 15+ diagnostic patterns
- **hct-benchmarks**: [github.com/stefanwiest/hct-benchmarks](https://github.com/stefanwiest/hct-benchmarks) — Validation suite

## Author

**Stefan Wiest**
- Web: [stefanwiest.de](https://stefanwiest.de)
- GitHub: [skew202](https://github.com/skew202)
- Writing: [SeekingSota](https://seekingsota.com)

## License

MIT License — See [LICENSE](LICENSE) for details.

---

*Part of the [Stefan Wiest](https://github.com/stefanwiest) ecosystem: AI Research & Engineering · Multi-Agent System Coordination*