Open Source

Express urgency, timing, and synchronization in any agent stack.

Two protocol extensions. Seven coordination signals. Four languages each.

🎯 The Problem

MCP connects agents to tools. A2A connects agents to each other. But neither tells agents when to act, how urgently, or whether to wait for approval.

Without coordination signals, developers build brittle ad-hoc state machines that break at scale.

💡 The Solution: 7 Musical Signals

Borrowed from centuries of ensemble coordination, these signals work anywhere:

📦 HCT-MCP Signals

For Anthropic MCP Protocol — The coordination layer that MCP is missing.

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")

→ View on GitHub · → Read the Spec

🔗 HCT-A2A Extension

For Google A2A Protocol — Coordination semantics for decentralized agent meshes.

{
  "extensions": [{
    "uri": "https://github.com/stefanwiest/hct-a2a",
    "description": "HCT coordination signals for multi-agent orchestration"
  }]
}

Polyglot Samples — Conductor/Performer pattern in 4 languages:

→ View on GitHub · → Read the Spec

⚡ Quick Start

# MCP Extension
pip install hct-mcp-signals          # Python
npm install @hct-mcp/signals         # Node.js
cargo add hct-mcp-signals            # Rust
go get github.com/stefanwiest/hct-mcp-signals/go  # Go

# A2A Extension
git clone https://github.com/stefanwiest/hct-a2a
cd hct-a2a/samples/python && python conductor.py

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