DOM and snapshot first
fast_snapshot, fast_click, fast_fill, fast_nav, fast_list, fast_switch, and console/network tools make ordinary pages cheap and structured.
MCP · Chrome extension · vision fallback
Browser automation for pages that fight back.
FastLink connects Claude Code, Claude Desktop, or claude.ai web to the Chrome tab a user is actually looking at. It reads DOM snapshots, clicks, fills, runs JS, watches console/network, and falls back to visual grounding when page structure disappears.
active tab · opaque iframe · form recovered
The tools are built for failure modes.
Vision when needed
fast_point, fast_point_som, fast_fill_vision, fast_locate, and fast_do handle canvas, iframes, custom widgets, and pages that serialize poorly.
Connection diagnostics
fast_status and fast_profile expose extension state, selected install slot, and deterministic routing for primary and secondary Chrome profiles.
1
Local install
Node MCP server auto-spawns a broker; Chrome extension connects to broker ports 9876 and 9877.
2
Desktop bundle
The same fast-dxt source builds the Claude Desktop .mcpb runtime.
3
Cloud relay
Cloudflare Worker and Durable Objects let claude.ai web reach a paired browser.
4
Updater paths
Git-pull and download-swap scripts keep unpacked extension installs current without pretending Chrome can silently reinstall them.
Why it exists
Real websites are not polite automation targets. They hide fields in iframes, render controls in overlays, mutate after clicks, cache stale frames, and break localhost after laptop sleep. FastLink’s job is to give the agent a ladder: structured DOM when possible, visual grounding when necessary, and clear diagnostics when the browser is not connected.
Recovery paths are part of the product
When the extension is absent
fast_status reports whether the browser is connected and returns connection diagnostics instead of making every other tool fail mysteriously.
When there are two profiles
fast_profile pins the session to primary, secondary, or auto so a second Chrome profile does not silently receive the wrong action.
When WSL networking drifts
The extension dials localhost first and falls back to the WSL VM IP; the broker binds broadly enough to keep that fallback path usable.
DOM
Fast path
Snapshot, click, fill, nav, wait, and tab tools are optimized for structured pages and return fresh post-action views where possible.
IMG
Visual path
Set-of-Mark, point location, and whole-form visual fill are reserved for the cases where the page cannot be read reliably from the DOM.
FastLink is a ladder, not one magic command
Simple pages use structured DOM tools. Heavy pages escalate to overlay scans, then screenshots interpreted by Gemini-backed tools. Connection problems use status and profile tools. Install/update problems use docs and scripts. That separation is why the agent can recover instead of blindly retrying the same failed click.
WS
Shared broker
The server auto-spawns the WebSocket broker and multiple MCP clients can reuse the same extension connection.
P1
Primary profile
The default Chrome profile connects on its own slot and can be targeted deterministically.
P2
Secondary profile
A second install can use a separate port so testing and real browsing do not collide.
CF
Cloud relay
The relay mirrors the local tool surface for claude.ai web through a paired browser session.