MCP Guide

The agent image ships with two preloaded MCPs: Playwright MCP and Email MCP. Both are installed as system services managed by supervisor and are not running by default. The run-qa command starts both MCPs at the beginning of each test run so that any configuration changes are picked up, and terminates them when the run ends.

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Playwright MCP

Provides tools for browser automation.

GitHub	https://github.com/microsoft/playwright-mcp
Installed version	v0.0.75
File directory	/services/playwright
Preinstalled browser	Chromium
Default config file	/services/playwright/playwright-mcp-config.json

playwright-mcp-config.json (default)

{
  "browser": {
    "browserName": "chromium",
    "launchOptions": {
      "args": [
        "--disable-gpu",
        "--disable-setuid-sandbox"
      ]
    },
    "snapshot": {
      "mode": "none"
    }
  }
}

URL Permissions

When Playwright MCP starts, it reads allowed-domains.yaml to determine which URLs the agent is permitted to access. Any attempt to visit a URL not on the list returns an error immediately.

allowed-domains.yaml can be placed either under /services/playwright or /agent/instructions/. The latter is recommended as it is mounted from the host and survives container restarts.

The file contains a single array property allowed listing all permitted origins.

allowed-domains.yaml (example)

allowed:
  # Wikipedia — root domain and English subdomain listed separately
  - https://www.wikipedia.org
  - https://en.wikipedia.org

  # Local app on a specific port
  - http://host.docker.internal:8080

  # Staging subdomains
  - https://app.staging.example.com
  - https://api.staging.example.com

tip

When testing a website running on your local machine, replace localhost with host.docker.internal. For example, http://localhost:8080 becomes http://host.docker.internal:8080.

Format Rules

Format	Example	What It Matches	What It Does NOT Match
Full origin	https://example.com	Only https://example.com on port 443	http://example.com, https://sub.example.com, https://example.com:8080
Full origin with port	https://example.com:8080	Only https://example.com:8080	Any other port on the same host
Wildcard subdomain	https://*.example.com	Any subdomain of example.com over HTTPS	https://example.com (root domain itself)

Behavior Rules

Rule	Detail
Subdomains are not included automatically	https://wikipedia.org does NOT cover https://en.wikipedia.org. Each subdomain must be listed separately.
Protocol is exact	https://example.com and http://example.com are different origins and must be listed separately.
Port is exact	https://example.com does not cover https://example.com:8080. They must be listed as separate entries.
Path is ignored	https://example.com/app and https://example.com/admin are treated as the same origin. Access cannot be restricted by path.
Redirects are not affected	If an allowed origin redirects to a blocked one, the redirect is still followed. This is not a security boundary.

Environment Variables

Variable	Description	Default
ENABLE_PLAYWRIGHT_MCP	Enable Playwright MCP	true
FIREWALL_DEBUG	Enable firewall debug logs	false

warning

The agent will not start if Playwright MCP is disabled.

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Email MCP

Provides simple email utilities for sending and receiving emails during tests. This MCP can be ignored if no email operations are required.

GitHub	https://github.com/taodong/duotail-test-sender
Installed version	v0.5.1
File directory	/services/email
Default config file	/services/email/email-mcp.properties

For full configuration and usage details, refer to the Email MCP README.

Environment Variables

Variable	Description	Default
ENABLE_EMAIL_MCP	Enable Email MCP	true
MAIL_HOST	SMTP host for sending email	localhost
MAIL_PORT	SMTP port for sending email	25
MAILHOG_URL	MailHog URL for checking received emails	http://localhost:8025
EMAIL_PERM_FILE	Path to the email permissions file	/agent/instructions/email-permissions.yaml

warning

If ENABLE_EMAIL_MCP is set to false, also remove the email entry from /agent/config/mcp-config.json so the agent does not attempt to connect to a server that is not running.