RabbitMQ MassTransit Server

An MCP (Model Context Protocol) server for RabbitMQ with MassTransit intelligence — error queue parsing, fault analysis, and message republishing.

Built for teams debugging async messaging issues across .NET microservices. Goes beyond basic queue management by understanding MassTransit conventions: _error/_skipped queues, the message envelope format, and fault message parsing.

Features

• 18 tools for complete RabbitMQ management via Claude Code
• MassTransit-aware: Automatically detects and parses _error/_skipped queues, fault envelopes, and message type URNs
• Parsed error output: Exception types, messages, stack traces, consumer types, retry counts, and original payloads — extracted from MT-Fault-* message headers
• Republish from error: The killer feature — fetch faulted messages and republish them for reprocessing
• Safe defaults: Mutative tools disabled by default, two-step confirmation for destructive operations

Quickstart

1. Add to your Claude Code config (~/.claude.json or project .claude.json):

{
  "mcpServers": {
    "rabbitmq": {
      "command": "npx",
      "args": ["-y", "@stevepic95/rabbitmq-masstransit-mcp@latest"],
      "env": {
        "RABBITMQ_HOST": "your-rabbitmq-host",
        "RABBITMQ_USERNAME": "your-username",
        "RABBITMQ_PASSWORD": "your-password"
      }
    }
  }
}

2. Restart Claude Code to load the new MCP server.

3. Start using it. Ask Claude things like:

• "Are there any error queues with messages?"
• "Show me the faults in the submit-order error queue"
• "What queues have no consumers?"
• "How many messages are in the report queue?"

That's it. The 13 read-only tools are available immediately — no flags needed.

To enable write operations (purge, delete, publish, republish), set "ALLOW_MUTATIVE_TOOLS": "true" in the env config.

Installation

npx @stevepic95/rabbitmq-masstransit-mcp@latest

Claude Code Configuration

Add to your .claude.json under mcpServers:

{
  "mcpServers": {
    "rabbitmq": {
      "command": "npx",
      "args": ["-y", "@stevepic95/rabbitmq-masstransit-mcp@latest"],
      "env": {
        "RABBITMQ_HOST": "your-rabbitmq-host",
        "RABBITMQ_PORT": "15672",
        "RABBITMQ_USERNAME": "your-username",
        "RABBITMQ_PASSWORD": "your-password",
        "RABBITMQ_VHOST": "/",
        "RABBITMQ_SSL": "false",
        "ALLOW_MUTATIVE_TOOLS": "false"
      }
    }
  }
}

For local development:

{
  "mcpServers": {
    "rabbitmq": {
      "command": "node",
      "args": ["/path/to/rabbitmq-masstransit-mcp/dist/index.js"],
      "env": {
        "RABBITMQ_HOST": "localhost",
        "RABBITMQ_USERNAME": "guest",
        "RABBITMQ_PASSWORD": "guest"
      }
    }
  }
}

Configuration

Variable	Required	Default	Description
RABBITMQ_HOST	Yes	—	RabbitMQ Management API hostname
RABBITMQ_PORT	No	15672	Management API port
RABBITMQ_USERNAME	Yes	—	Authentication username
RABBITMQ_PASSWORD	Yes	—	Authentication password
RABBITMQ_VHOST	No	/	Default virtual host
RABBITMQ_SSL	No	false	Use HTTPS for Management API
ALLOW_MUTATIVE_TOOLS	No	false	Enable mutative tools (purge, delete, publish, republish, move)

You can also enable mutative tools via CLI flag: --allow-mutative-tools

Tools

Read-Only (13 tools) — Always available

Tool	Description
get_overview	Cluster stats: queue totals, connection counts, message rates
list_queues	List queues with depth, consumer count, rates. Filter by vhost, name pattern
get_queue	Detailed queue stats: depth, rates, consumers, memory, policy
list_exchanges	List exchanges. Filter by vhost, type
get_exchange	Exchange details and bindings
list_bindings	List bindings for a queue or exchange
list_connections	Active connections with client info
list_consumers	Active consumers with queue assignments
peek_messages	Browse messages without consuming (non-destructive)
list_error_queues	Find all _error queues with message counts
list_skipped_queues	Find all _skipped queues with message counts
peek_errors	Browse error queue messages with parsed fault details
get_queue_health	Quick health check: no consumers, growing depth, high error counts

Mutative (5 tools) — Require ALLOW_MUTATIVE_TOOLS=true

Tool	Description
purge_queue	Purge all messages from a queue
delete_queue	Delete a queue
publish_message	Publish a message to an exchange
republish_from_error	Republish faulted messages from _error queue to original exchange
move_messages	Move messages from one queue to another

MassTransit Intelligence

Error Queue Parsing

peek_errors doesn't just dump raw JSON — it reads MT-Fault-* headers that MassTransit attaches when moving messages to error queues, giving you everything you need to debug the failure:

Queue: submit-order_error (3 messages)

Message 1:
  Faulted: 2026-02-15T14:30:05Z
  Reason: fault
  Message Type: MyApp.Messages.OrderSubmitted
  Consumer: MyApp.Consumers.SubmitOrderConsumer
  Exception: Microsoft.Data.SqlClient.SqlException - "Arithmetic overflow error converting numeric to data type numeric."
  Retry Count: 5
  Stack Trace:
    at Microsoft.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(...)
    at MyApp.Data.OrderRepository.GetFees(Int32 orderId) in /src/OrderRepository.cs:line 35
    at MyApp.Services.OrderService.Process(Int32 id) in /src/OrderService.cs:line 51
    at MyApp.Consumers.SubmitOrderConsumer.Consume(ConsumeContext`1 context) in /src/SubmitOrderConsumer.cs:line 11
  Original Payload: { "orderId": "abc-123", "amount": 99.99 }
  Source Host: order-service-swrm-app1b-p02 / order-service (PID 1)
  Assembly: order-service v1.0.3.0 (.NET 8.0.8)

Republish from Error (Two-Step)

The highest-value tool for debugging. First call previews the messages:

> republish_from_error(errorQueue: "submit-order_error", count: 3)

Preview: 3 message(s) from "submit-order_error" ready to republish:
[... parsed fault details ...]

To republish these messages, call again with confirm=true and count=3.

Second call with confirm: true actually consumes and republishes:

> republish_from_error(errorQueue: "submit-order_error", count: 3, confirm: true)

Republished 3/3 message(s) from "submit-order_error".

Queue Health Check

Quick overview of potential issues across all queues:

> get_queue_health()

⚠ Queues with NO consumers and messages (2):
  order-processing — 150 message(s)
  notification-sender — 42 message(s)

✗ Error queues with messages (3 queues, 89 total):
  submit-order_error — 45 message(s)
  payment-process_error — 32 message(s)
  email-send_error — 12 message(s)

△ High depth queues (>1000 messages, 1):
  analytics-events — 15234 message(s), 2 consumer(s)

Requirements

• Node.js >= 18.0.0
• RabbitMQ with Management Plugin enabled (port 15672)

License

MIT