MCP SERVERBreak the network under a real page, then check whether the app handled it.
LABSCO SUMMARY
It hands an agent the controls to make the payment API return 503, stall the dashboard for three seconds, or cut the connection right after the order is submitted — and then reports whether the error boundary actually appeared, instead of leaving that to a screenshot.
Network chaos control over Playwright sessions: it intercepts requests matching a URL pattern and makes them fail, stall, drop or return corrupt data, then reports what the page did about it.
Playwright, and a URL the browser can reach. Published on npm as playwright-network-chaos-mcp.
One command — npx -y playwright-network-chaos-mcp
USE CASES
Force the API to an error status and name the selector the app should show; the verdict says whether it appeared.
Add latency with jitter to the matching requests and watch for the loading selector during the wait.
Block the analytics or CDN pattern and see whether the page still renders and still works.
Abort the request after a delay, or inject an OS-level error code, so the failure lands where it actually hurts.
Fail the first N requests and let the rest through; if the app recovers, the retry path is real.
Return a malformed body and see whether the parser fails loudly or corrupts the UI quietly.
Counted once with only startup setup. Other versions, modes or optional credentials may expose a different list.
assert_chaos_handledInjects a chaos HTTP status into all matching requests, then returns a structured verdict: did the app show a fallback UI, were there unhandled JS exceptions, and did it survive? Use to answer: is the app chaos-resilient — does it show a recovery UI without throwing exceptions?
block_resourcesBlocks requests to specified URL patterns — useful for simulating third-party outages (analytics, CDNs, tracking). Use to answer: does the app still load and function if Google Analytics or a CDN is down?
inject_latencyAdds artificial delay to requests matching a URL pattern, simulating slow networks or overloaded APIs. Use to answer: does the app show loading states when the API takes 3 seconds? Does it time out gracefully?
inject_response_corruptionIntercepts requests matching a URL pattern and returns a malformed or corrupted response, simulating partial network failures at the protocol level. Use to answer: does the app handle malformed JSON, content-length lies, or truncated payloads without crashing?
simulate_api_failureIntercepts API requests matching a URL pattern and makes them return an error status code. Navigates to the page and checks if a fallback UI element appears. Use to answer: does the app show a proper error state when the payment API returns 503?
simulate_network_dropAborts requests matching a pattern after a delay, simulating a mid-flight connection drop. Use to answer: what happens if the network drops after the order request is sent but before the response arrives?
simulate_stateful_failureIntercepts requests matching a URL pattern and fails the first N requests with an error status, then lets subsequent requests succeed. Simulates transient failures and tests retry/recovery logic. Use to answer: does the app retry after a 503 and recover when the service comes back?
trigger_system_network_errorAborts requests matching a URL pattern with a system-level network error code, simulating OS-level failures like unreachable hosts or access denied. Use to answer: does the app recover when the DNS resolution fails or the OS rejects a connection?
BEFORE YOU INSTALL
8 tools when we connected.
npx on PATH
CONTEXT COST
Rated by the size of the 8 tool definitions that ride along on every turn, not by how many there are
INSTALLATION
Add the block to your client, or run the command directly.
{
"mcpServers": {
"playwright-network-chaos-mcp": {
"command": "npx",
"args": [
"-y",
"playwright-network-chaos-mcp"
]
}
}
}npx -y playwright-network-chaos-mcpMCP servers
segentic-lab
asume21
currents-dev
tactual-dev