Browser Inspection
Overview
Two browser MCP servers are available with different strengths. This skill helps choose the right one based on your needs.
Critical Rule
Authentication trumps debugging features.
DevTools opens a FRESH browser session - it has NO access to the user's existing tabs, cookies, or login state. If the page requires authentication:
- DevTools will show a login page, not the user's logged-in view
- You MUST use Browser MCP first, even if you want debugging features
- Browser MCP has basic console logs - use those when login is required
When to Use
Use this skill when:
- User says "check the browser", "look at the browser", "inspect the page"
- You need to debug frontend/UI issues
- You need to see what's displayed in the browser
- You need to interact with a web page
Decision Flowchart
digraph browser_decision {
rankdir=TB;
start [label="Need browser access" shape=ellipse];
q1 [label="Need logged-in\nsession/cookies?" shape=diamond];
q2 [label="Need debugging?\n(network/console/perf)" shape=diamond];
q3 [label="Quick visual\ncheck only?" shape=diamond];
browser [label="Browser MCP\n(existing sessions)" shape=box style=filled fillcolor=lightblue];
devtools [label="DevTools MCP\n(debugging tools)" shape=box style=filled fillcolor=lightyellow];
start -> q1;
q1 -> browser [label="Yes"];
q1 -> q2 [label="No"];
q2 -> devtools [label="Yes"];
q2 -> q3 [label="No"];
q3 -> browser [label="Yes"];
q3 -> devtools [label="No\n(clean state)"];
}
Quick Decision Matrix
| Scenario | Use | Why |
|---|---|---|
| See logged-in state | Browser MCP | Connects to existing sessions |
| Debug console errors | DevTools | Better console message tools with filtering |
| Inspect network requests | DevTools | Has network request inspection |
| Performance profiling | DevTools | Has performance trace tools |
| Quick visual check | Browser MCP | Simpler, faster setup |
| Test in clean state | DevTools | Fresh session, no cookies/login |
| Interact with user's open tab | Browser MCP | Sees existing tabs |
| Evaluate JavaScript in page | DevTools | Has evaluate_script tool |
| Emulate mobile/slow network | DevTools | Has emulation capabilities |
MCP Guidelines
For detailed usage of each MCP, see:
- Browser MCP Guidelines - For existing sessions and quick checks
- DevTools MCP Guidelines - For debugging and performance analysis
Default Recommendation
Start with Browser MCP if:
- You need to see something the user is looking at
- The page requires authentication
- You just need a quick snapshot
Start with DevTools MCP if:
- You're debugging an error on a PUBLIC page (no login required)
- You need to inspect network requests or console logs
- You need to test in a clean environment
Common Mistakes
❌ "Debug console errors on logged-in app" → picks DevTools ✅ Use Browser MCP - DevTools can't access the logged-in session
❌ Thinking DevTools can "connect to" the user's session ✅ DevTools always opens a fresh session - no cookies, no login
❌ Prioritizing "better debugging tools" over session access ✅ Authentication requirement is the first decision point - it overrides everything
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