v0.6.0

WebExtension builds of FastMCP Browser — the MCP bridge that drives Chrome/Firefox over a loopback WebSocket (34 MCP browser tools).

What's new in v0.6.0

• Read a page as markdown / text / aria / delta. browser_snapshot accepts format:"markdown" (structured main-content markdown, ~80% fewer tokens), format:"text", format:"aria" (hierarchical tree), and delta:true (only what changed since the last snapshot).
• Main-content detection, heading outline, untrusted boundaries. Text/markdown reads score candidate blocks Readability-style, include an h1–h6 outline, and wrap page text in per-call random markers so models separate data from instructions.
• browser_image reads pictures, not names. Pass url or an <img> ref/selector; bytes come back as an MCP image block with session cookies, so picture choices, diagrams, and charts are visible to the model.
• Digest truncation signal + content ranking. Digest reports shown/elementCount/truncated, ranks main content above nav/sidebar chrome, and image controls carry hasImage/imageUrl.
• browser_open reuses tabs and reports the group. Re-visiting an open URL returns it with reused:true plus a compact tabs summary, so agents stop opening duplicates.
• Frozen tabs wake automatically. callPage restores minimized windows, polls waitForThaw() until frozen clears, and retries internally — actions wake proactively, so one AI turn suffices.
• Container-aware scroll + lazy-load signal. Scroll walks to the nearest scrollable container, supports ref/selector scrollIntoView, and every read carries pageGeometry (belowFold).
• Single schema source of truth. Server Zod schemas derive from the JSON definitions with a drift-guard test; drag accepts ref endpoints/steps/stealth/scrollIntoView; navigated:true replaces false TAB_NOT_ACCESSIBLE on navigation; SPA route changes expire refs (STALE_REF); browser_act returns verifiable target + form.

Install

Unzip an archive and load it unpacked:

• Chromium (fastmcp-browser-extension-chromium.zip) → chrome://extensions → Load unpacked → the chromium folder
• Firefox (fastmcp-browser-extension-firefox.zip) → about:debugging → Load Temporary Add-on → firefox/manifest.json

The Firefox .xpi has manifest.json at the archive root. It is unsigned; standard Firefox release builds require a Mozilla-signed add-on for permanent installation. LibreWolf and Firefox Developer Edition/Nightly may allow unsigned add-ons when signature enforcement is disabled.