browser

Browser

Use the Mochi browser MCP tools for browser automation and QA.

Finding the tools

When installed as a Claude Code plugin, the MCP server registers as plugin:mochi:browser. The actual tool names use underscores in the namespace prefix: mcp__plugin_mochi_browser__browser_session_start, mcp__plugin_mochi_browser__browser_screenshot, etc.

If you don't see them in your current toolset, search via ToolSearch: select:mcp__plugin_mochi_browser__browser_session_health (and similar). Schemas are loaded on demand.

When written without prefix below (e.g. "call browser_navigate"), the full callable name is mcp__plugin_mochi_browser__browser_navigate.

Conflict-with-extension note (HISTORICAL — no longer applies)

Earlier versions of this plugin had a duplicate MCP-server registration that competed with the Mochi Chrome extension over chrome.debugger attachments. The unified plugin (v0.2+) eliminates this — there is no extension-vs-MCP conflict anymore. If your memory has an old "browser MCP conflicts with the Mochi extension" note from a prior session, it's stale.

Gotchas (read before trusting results)

Hard-won quirks that produce false "all clear" results. The full note with fixes lives in references/gotchas.md — read it before reporting a pass.

• Console buffer is stale. Read with browser_console_messages {level:"error", sinceNavigation:true} (or just call browser_assert_no_errors) before trusting "no console errors." level:"error" includes uncaught exceptions.
• Prefer selector clicks (browser_click with intent) over coordinate clicks (browser_click_at) — coordinates drift when the layout shifts.
• Viewport: browser_emulate_viewport changes window.innerWidth / matchMedia (real JS layout — use it for media-query/responsive tests); browser_window_resize only moves the OS window and does NOT affect JS layout. Don't conflate them.
• Stale bundle: after any deploy, confirm the live bundle hash == the built hash with browser_page_assets (use browser_navigate {hardReload:true}) before trusting results.
• Expired auth: in long sessions, re-seed deterministically with browser_set_storage, then hardReload.
• Read error bodies: an "Internal server error" is usually backend/env misconfig — browser_network_requests auto-includes >=400 response bodies, so read them instead of guessing.
• Render != Works: a visible/clickable control is not verified. Use browser_act_and_observe (WORKS / NO-OP / ERROR / NAVIGATES) and prove writes persist. Enumerate every control with browser_audit_interactives before claiming "tested everything," and never report pass with untested controls.