browser-tools-mcp

Persistent, headed Chromium browser control for OpenCode/Claude Code, in the style of Claude Code's browser tool. Built 2026-08-05 because OpenCode had no native browser tool and custom-scraper (plain HTTP) can't read JS-heavy or login-walled pages.

Architecture

The MCP server process is the singleton browser manager. Because OpenCode keeps the stdio server alive for the whole CLI session, the browser survives across agent turns. If the browser crashes or the window is closed, the next tool call transparently relaunches it (server/browser.js).

Launch config: headless: false, slowMo: 100, viewport 1280x800, desktop Chrome UA, --disable-blink-features=AutomationControlled.

Files

server/server.js — MCP entrypoint, registers the five tools + schemas.
server/browser.js — singleton browser/context/page manager + relaunch logic.
server/tools.js — the operations (interactable tree, targeting, highlight, screenshots).
server/_self_verify.js — standalone scenario test: npm run verify.
shots/ — screenshots from browser_inspect.
USAGE.md — agent-facing rules (wired into OpenCode instructions).

Tools

Tool	Purpose
`browser_navigate(url)`	Load a URL; returns final URL + title.
`browser_inspect()`	Screenshot + interactable element tree with numeric targets.
`browser_click(target)`	Click by inspect number, CSS selector, or visible text.
`browser_fill(target, value)`	Type into a field by number/selector/text.
`browser_request_human(message)`	Pause flow and surface a question to the human.

Element targeting matches the Claude Code convention: browser_inspect assigns each interactable element a numeric target, tagged in the DOM as data-bt-target so later actions resolve the exact same element (visible- filtered indices would drift against unfiltered .nth() on pages with hidden inputs). Elements are highlighted briefly before clicking so the user sees the action.

Verification

npm run verify        # navigate -> inspect -> click -> fill -> crash-recovery

Verified 2026-08-05: example.com navigate/inspect/click, Google fill by target, and relaunch-after-kill all pass; all five tools registered and responded over the real MCP stdio protocol.

Operational notes

Headed means a desktop. The Chromium window needs an interactive session to launch; on a headless/disconnected box the launch fails — report that rather than pretending.
Isolated browser. This is NOT Luigi's logged-in Chrome (that's chrome-bridge). No logged-in sessions, no extensions, full write access.
Human-gated. No logins/orders/sends without explicit instruction; browser_request_human means STOP until the human answers.
Registered in ~/.config/opencode/opencode.jsonc as the browser-tools MCP server; usage rules wired into instructions via USAGE.md.