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@miroslavmyrhaMCP server · External

Shows an AI assistant the last cypress run: command log, errors, screenshots, DOM of failed tests.

Software testingv0.1.2MITTypeScript
Freeno charge per call
How to install

Runs on your machine from its package; the steps are below.

What it does

  1. Reads
  2. Writes
  3. High impact

Not assessed yet.

What it costs

Free

Odel charges nothing per call. The publisher may charge for its own service.

Runs locally over stdio

This server isn't hosted — your MCP client launches it from a package registry. Use one of the commands below, or drop the config into your client (e.g. Claude Desktop).

npm@miroslavmyrha/cypress-mcpv0.1.2

Run

npx -y @miroslavmyrha/cypress-mcp

MCP client config

{
  "mcpServers": {
    "cypress": {
      "command": "npx",
      "args": [
        "-y",
        "@miroslavmyrha/cypress-mcp"
      ]
    }
  }
}
README6 min read

cypress-mcp

npm CI License: MIT

MCP server that shows an AI assistant what happened in your last cypress run: which commands each test ran, what failed, the error, a screenshot, and the page as it was at the moment of the failure.

It is made for headless runs, on your machine and in CI. That is the place the official tools do not reach, see How it compares.

bash
npm install -D @miroslavmyrha/cypress-mcp

Example

A spec with three tests, the last of which fails:

js
it('shows a counter of finished items', () => {
  cy.get('.todo-list li').first().find('input[type=checkbox]').check()
  cy.get('[data-test=finished-count]').should('contain', '1')
})

After cypress run, the assistant calls get_last_run and gets the commands that ran, the error and the path of a DOM snapshot (output shortened):

json
{
  "title": "Todo list > shows a counter of finished items",
  "state": "failed",
  "domSnapshotPath": "snapshots/cypress-e2e-todo-cy-js/todo-list-shows-a-counter-of-finished-items-d963bb8d.html",
  "commands": [
    { "name": "visit", "message": "https://example.cypress.io/todo" },
    { "name": "get", "message": ".todo-list li" },
    { "name": "first", "message": "" },
    { "name": "find", "message": "input[type=checkbox]" },
    { "name": "check", "message": "" },
    { "name": "get", "message": "[data-test=finished-count]" }
  ],
  "error": "AssertionError: Timed out retrying after 2000ms: Expected to find element: `[data-test=finished-count]`, but never found it."
}

It can then look into the page as it was when the test failed. query_dom with the selector .todo-count:

json
{
  "selector": ".todo-count",
  "totalMatches": 1,
  "results": [
    {
      "breadcrumb": "body > section.todoapp-wrapper > div.todoapp > footer.footer > span.todo-count",
      "outerHTML": "<span class=\"todo-count\"><strong>1</strong> item left</span>"
    }
  ]
}

So the counter exists, under another selector, and the assistant can fix the test without anyone pasting logs into the chat.

How it works

cypress run → tests run
  → support/index.ts captures Cypress command log per test
  → cy.task('mcpSaveTestLog') transfers logs to node side
  → plugin/index.ts stores logs in memory
  → after:spec → merges logs + results → writes .cypress-mcp/last-run.json

Claude → MCP server → get_last_run → reads last-run.json

How it compares

Cypress has two tools of its own for AI assistants. They cover other situations than this one.

this packagecypress tapCypress Cloud MCP
Readsthe last local cypress runa live cypress open sessionruns recorded to Cypress Cloud
Headless runs and CIyesnoonly what was recorded
Command log and DOM of a failed testyesyesno, links to Test Replay
NeedsCypress 12 or newer, a plugin and a support importCypress 15.21 or newer, a Chromium browsera Cypress Cloud account
InterfaceMCP (stdio or HTTP)command lineMCP

Use cypress tap while you write a test with the Cypress app open. Use this package when the tests run headless and the assistant should see why one failed.

The results are written in the after:spec event, which Cypress fires in run mode. In cypress open that event needs experimentalInteractiveRunEvents.

Before anything reaches the assistant, values that look like secrets are redacted, and content that comes from the tested application is marked as untrusted data.

Setup

1. Install

bash
npm install -D @miroslavmyrha/cypress-mcp

Note: the unscoped cypress-mcp name on npm belongs to an unrelated project. Always use the scoped @miroslavmyrha/cypress-mcp.

2. Register the plugin in cypress.config.ts

typescript
import { defineConfig } from 'cypress'
import { cypressMcpPlugin } from '@miroslavmyrha/cypress-mcp/plugin'

export default defineConfig({
  e2e: {
    setupNodeEvents(on, config) {
      cypressMcpPlugin(on, config)
    },
  },
})

3. Import support in cypress/support/e2e.ts

typescript
import '@miroslavmyrha/cypress-mcp/support'

4a. Configure Claude Desktop / Claude Code (stdio transport)

In your MCP settings (~/.config/claude/claude_desktop_config.json or claude mcp add):

json
{
  "mcpServers": {
    "cypress": {
      "command": "npx",
      "args": ["-y", "@miroslavmyrha/cypress-mcp", "--project", "/absolute/path/to/your/project"]
    }
  }
}

Or with claude mcp add:

bash
claude mcp add cypress -- npx -y @miroslavmyrha/cypress-mcp --project /absolute/path/to/your/project

4b. HTTP transport (Ollama, custom bridges)

bash
# Start MCP server in HTTP mode (random token printed to stderr)
npx -y @miroslavmyrha/cypress-mcp --project /path/to/project --transport http --port 3333

# Or with a fixed token for automated deployments
MCP_HTTP_TOKEN=$(openssl rand -hex 32) npx -y @miroslavmyrha/cypress-mcp --project /path/to/project --transport http --port 3333

# Server listens on:
#   POST http://localhost:3333/mcp  → tool calls (MCP Streamable HTTP)

MCP Tools

ToolDescription
list_specsList all Cypress spec files. Optional pattern glob (default: **/*.cy.{ts,js,tsx,jsx})
read_specRead a spec file's content by relative path
get_configRead the Cypress config file (cypress.config.ts/js/mjs/cjs), secret-looking values redacted
get_last_runGet results of the last test run: states, errors, command log, DOM snapshots
get_screenshotGet a screenshot from the last run. Returns the image itself (up to 2 MB) plus path and size metadata
query_domQuery the DOM snapshot of a failed test using a CSS selector
run_specRun a single Cypress spec file and wait for completion. Returns exit code and summary

Output format of .cypress-mcp/last-run.json

json
{
  "timestamp": "2026-02-18T22:00:00Z",
  "specs": [
    {
      "spec": "cypress/e2e/login.cy.ts",
      "stats": { "passes": 3, "failures": 1, "pending": 0, "skipped": 0, "duration": 5230 },
      "screenshots": ["/abs/path/to/Login -- should show error (failed).png"],
      "tests": [
        {
          "title": "Login > should login with valid credentials",
          "state": "passed",
          "duration": 1200,
          "error": null,
          "domSnapshotPath": null,
          "commands": [
            { "name": "visit", "message": "/login" },
            { "name": "get", "message": "#email" },
            { "name": "type", "message": "test@example.com" }
          ],
          "consoleErrors": [],
          "networkErrors": []
        },
        {
          "title": "Login > should show error on invalid password",
          "state": "failed",
          "duration": 800,
          "error": "Timed out retrying: Expected to find element: .error-message",
          "domSnapshotPath": "snapshots/cypress-e2e-login-cy-ts/login--should-show-error-a1b2c3.html",
          "commands": [...],
          "consoleErrors": ["Uncaught TypeError: Cannot read property 'x' of null"],
          "networkErrors": [{ "method": "POST", "url": "/api/login", "status": 500 }]
        }
      ]
    },
    {
      "spec": "cypress/e2e/dashboard.cy.ts",
      "stats": { ... },
      "screenshots": [],
      "tests": [...]
    }
  ]
}

All specs from a run are captured. In cypress run the accumulator resets on before:run. In cypress open results accumulate for the lifetime of the Cypress process. Failed tests include a domSnapshotPath pointing to an HTML file (up to 100 KB of document.body.outerHTML) stored under .cypress-mcp/snapshots/.

CLI options

Options:
  --project <path>     Cypress project root (default: current directory)
  --transport <type>   stdio or http (default: stdio)
  --port <number>      HTTP port, only for --transport http (default: 3333)
  -V, --version        Show version
  -h, --help           Show help

Add .cypress-mcp to .gitignore

gitignore
.cypress-mcp/

Environment variables

VariableDescription
MCP_HTTP_TOKENSet a fixed bearer token for HTTP transport (min 32 chars). If not set, a random token is generated on each start and printed to stderr.

Development

This project uses Bun as the package manager:

bash
bun install
bun run typecheck
bun run test
bun run build

Requirements

  • Node.js 18+
  • Cypress 12+ (developed and tested with Cypress 13)

Author

Miroslav Myrha

License

MIT

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