NATS MCP Server

What is NATS MCP Server?

NATS MCP Server is a Model Context Protocol server that provides access to NATS, a cloud-native messaging system, through the NATS CLI. It enables AI models to publish, subscribe to, and request-reply over NATS subjects.

How to use NATS MCP Server?

Install via npm (npm install @modelcontextprotocol/nats-mcp-server) or build from source. Configure with the NATS_URL environment variable (default nats://localhost:4222). Add the server to your MCP client’s configuration (e.g., Cline or Claude Desktop) and then invoke its tools: publish, subscribe, or request.

Key features of NATS MCP Server

• Publish messages with headers, templates, and reply subjects
• Subscribe to subjects with configurable timeouts and message counts
• Request-reply pattern support with optional headers
• Go template functions for dynamic message content
• Full NATS CLI integration and robust error handling

Use cases of NATS MCP Server

• AI assistants sending commands or events via NATS subjects
• Implementing request-reply service calls (e.g., asking a service for the time)
• Broadcasting messages to multiple subscribers with templates or headers
• Testing and debugging NATS messaging patterns from an MCP client

FAQ from NATS MCP Server

What are the required dependencies?

Node.js >= 14.0.0 and the NATS CLI (nats) installed on the system.

How do I install the NATS CLI?

Installation varies by OS: Homebrew on macOS (brew install nats), snap install nats on Linux, Chocolatey or Scoop on Windows, or build from source with Go.

How do I configure the NATS server URL?

Set the NATS_URL environment variable before starting the MCP server. Default is nats://localhost:4222.

What MCP tools does the server offer?

Three tools: publish (send messages with optional headers, templates, and reply subjects), subscribe (receive messages with timeout and count limits), and request (send a request and wait for a reply with optional headers).

Can I use templates in messages?

Yes. When template: true is set on publish, the message can use functions like {{Count}}, {{Time}}, {{Random min max}}, and others.