Selenium vs Skyvern

Selenium

Selenium is stable, Apache-2.0 software on 4.51.0 with bindings in five languages, CI passing on trunk, an llms.txt and an agent guide added in September 2026. It has no MCP server of its own, Selenium Manager sends usage statistics by default, and Grid accepts unauthenticated sessions unless a username and password are set.

Skyvern

The hosted MCP server annotates every tool as read-only or destructive and can advertise a 29 or 32-tool subset in place of 114, and the API has a written six-month deprecation policy. Every key and OAuth token carries full organisation authority, with no read-only or scoped credential, and no request rate limits are documented.

Selenium

1. Install with pip install selenium (Python 3.10 or later) and let Selenium Manager fetch drivers. Do not set driver paths
2. Use WebDriverWait with expected conditions, never fixed sleeps, and do not mix implicit and explicit waits
3. Set SE_AVOID_STATS=true to stop Selenium Manager sending usage statistics
4. Point coding agents at https://www.selenium.dev/llms.txt. Most Selenium 2 and 3 era examples use removed APIs
5. Set --username and --password before exposing a Grid beyond localhost. Check http://localhost:4444/status before creating sessions

Skyvern

1. Connect to https://api.skyvern.com/mcp/x/lean or /x/operate, or send X-Skyvern-Scope, so the client loads 32 or 29 tools. The scope filters the list and does not limit permissions
2. Use a separate Skyvern organisation for each blast radius. Any key or OAuth token can read and write stored credentials and delete workflows
3. Never pass passwords to skyvern_act or skyvern_type. Store them as credentials and call skyvern_login
4. Set max_steps on tasks, or x-max-steps-override on agent runs, to cap credits. A run that reaches the cap ends as timed_out
5. On 503 from POST /v1/run/agents, wait Retry-After seconds. No run was created, so resubmitting is safe