Skillget

mcp-chaos-rig

mcp
Guvenlik Denetimi
Basarisiz
Health Gecti
  • License — License: MIT
  • Description — Repository has a description
  • Active repo — Last push 0 days ago
  • Community trust — 10 GitHub stars
Code Basarisiz
  • rm -rf — Recursive force deletion command in package.json
  • process.env — Environment variable access in src/api.ts
  • exec() — Shell command execution in src/db.ts
  • process.env — Environment variable access in src/index.ts
  • process.env — Environment variable access in src/server.ts
  • Hardcoded secret — Potential hardcoded credential in src/state.ts
Permissions Gecti
  • Permissions — No dangerous permissions requested
Purpose
This tool is a local testing server designed for developers building MCP clients. It allows you to intentionally simulate API failures, authentication issues, and flaky tool responses on demand.

Security Assessment
Overall risk is rated as High. The automated audit raised several critical flags. It detected a potential hardcoded credential in the state file and found a recursive force deletion command in the package configuration. Additionally, the tool utilizes shell command execution in its database module. While accessing environment variables and making network requests are expected behaviors for an OAuth and server-testing utility, the combination of hardcoded secrets, destructive file deletion commands, and shell execution requires extreme caution. It should strictly be run in isolated, non-production environments.

Quality Assessment
The project exhibits solid foundational health. It is actively maintained, with the most recent code push occurring today, and is clearly documented to solve a specific developer problem. It uses a standard MIT license. However, community trust is currently very low, indicated by only 10 GitHub stars, meaning the codebase has not yet undergone widespread peer review.

Verdict
Use with caution—while extremely useful for testing, it contains risky code patterns and must only be run in secure, isolated development environments.
SUMMARY

A local MCP server that breaks on demand. Test your client against auth failures, disappearing tools, flaky responses, and token expiry, all from a web UI.

README.md

MCP Chaos Rig

MCP Chaos Rig

A local MCP server that breaks on demand. Test your client against auth failures, disappearing tools, flaky responses, and token expiry, all from a web UI.

npm version license downloads

The problem

You're building an MCP client. You need to test OAuth flows, token refresh, tool discovery, error handling, and session lifecycle. Production servers don't fail on command. You need a server that does.

What Chaos Rig does

Run a local MCP server where you control everything:

  • Break authentication: force 401s and 500s mid-session, expire tokens on demand, reject refresh tokens
  • Break tools: disable tools to trigger tools/changed, switch schema versions live
  • Break reliability: add random latency, make tool calls fail at configurable rates
  • See everything: live request log shows inbound JSON-RPC calls and outbound SSE responses, with click-to-expand bodies

Server tab

Test scenarios

Scenario How to test it
OAuth 2.1 consent flow Use the interactive consent page: approve, decline, invalid code, tampered state
Fixed header auth Switch to Headers mode, configure key-value pairs, verify client sends them
Missing/wrong headers Send requests with missing or mismatched headers — 401 with details
Token rejection mid-session Toggle "Reject OAuth" to 401 or 500 while client is connected
Token expiry and refresh Set access token TTL to a short value, watch the client refresh
Reject refresh tokens Toggle "Reject refresh tokens" to force re-authentication
Wrong client refreshing Enable "Enforce refresh token ownership" — catches clients that lose credentials and re-register
Scope discovery conflict Set different scopes in metadata vs WWW-Authenticate header, test which the client trusts
Tool disappearing Disable a tool in the Tools tab. Clients receive tools/changed
Tool schema changing Switch echo or add between v1 and v2 schemas
Flaky tool calls Set failure rate 0-100%. Failed calls return isError: true
Slow responses Enable slow mode with configurable latency range
PKCE code exchange OAuth consent page offers "Wrong Code" and "Wrong State" options
Database-backed tools CRUD operations on a real SQLite contact database

Quick start

npx mcp-chaos-rig

Control panel at localhost:4100/ui, MCP endpoint at http://localhost:4100/mcp. Requires Node 20+.

If you prefer a global install:

npm install -g mcp-chaos-rig
mcp-chaos-rig

Or run from source:

git clone https://github.com/Typewise/mcp-chaos-rig.git
cd mcp-chaos-rig
npm install
npm run dev

Remote access

If your production environment needs to reach Chaos Rig, expose it via a tunnel (ngrok, Cloudflare Tunnel, etc.) and set BASE_URL so OAuth redirects resolve correctly:

BASE_URL=https://your-tunnel.example.dev npx mcp-chaos-rig

Auth state

All state is in-memory and resets on restart. Bearer starts with token test-token-123 (valid until changed). OAuth tokens expire per TTL. Refresh tokens track ownership per client when enabled. After restart, do one refresh with ownership off to re-seed, then turn it on.

Control panel tabs

Server

Configure auth mode, slow mode (random latency), and flaky tools (% failure rate).

Auth mode Behavior
None All requests pass through
Bearer Requires Authorization: Bearer test-token-123
OAuth 2.1 Full authorization flow with interactive consent page

Bearer and OAuth modes support fault injection: force 401 or 500 responses to test error handling.

OAuth mode adds controls for access token TTL, refresh token rejection, and refresh token ownership enforcement. OAuth endpoints are listed in a collapsible section.

Tools

Tools tab

Toggle tools on/off. Disabling sends tools/changed to connected clients. Some tools (echo, add) support version switching.

Available tools:

  • echo: returns your message (v2 adds format options)
  • add: sums two numbers (v2 accepts an array)
  • get-time: current server time as ISO 8601
  • random-number: random integer in a range
  • reverse: reverses a string
  • list-contacts, search-contacts, create-contact, update-contact, delete-contact: SQLite CRUD

Contacts

Contacts tab

View and reset the SQLite database backing the contact tools. Starts with three seed records.

Log

Log tab

Live request log showing inbound requests and outbound SSE responses. Displays timestamp, source (mcp/auth/sse), method, status, JSON-RPC method, tool name, and arguments. Click any truncated body or args line to expand it. Keeps last 200 entries.

OAuth consent page

OAuth consent page

When auth mode is OAuth, the authorization endpoint shows an interactive consent page:

Button Result
Approve Redirects with valid authorization code
Decline Redirects with error=access_denied
Wrong Code Redirects with invalid code (token exchange fails)
Wrong State Redirects with tampered state parameter

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