Add optional 'expression' parameter to browser_console that evaluates
JavaScript in the page context (like DevTools console). Returns structured
results with auto-JSON parsing.
No new tool — extends the existing browser_console schema with ~20 tokens
of overhead instead of adding a 12th browser tool.
Both backends supported:
- Browserbase: uses agent-browser 'eval' command via CDP
- Camofox: uses /tabs/{tab_id}/eval endpoint with graceful degradation
E2E verified: string eval, number eval, structured JSON, DOM manipulation,
error handling, and original console-output mode all working.