Skip to main content
Glama
sgreen7979

browser-stream

by sgreen7979

browser-stream

MCP server that collapses browser act-then-observe into single tool calls. Every action returns its consequences — what appeared, disappeared, changed, or shifted — so agents see the effect of each action without a separate observation step.

~50% fewer tool calls. ~90% fewer tokens.

Tools

Tool

Description

browser_navigate

Navigate to a URL. Returns a snapshot of interactive elements.

browser_snapshot

Take a snapshot of the current page. Returns interactive elements with @e refs.

browser_click

Click an element by ref. Returns consequences.

browser_fill

Fill a text input by ref. Returns consequences.

browser_press_key

Press a key or key combination (e.g. Enter, Control+a). Returns consequences.

browser_scroll

Scroll the viewport or a container. Detects DOM churn and layout shifts.

browser_wait_for

Wait for text to appear or a ref to become visible. Polls every 500ms.

Related MCP server: Charlotte

Refs

Every interactive element gets a globally unique ref like @e1, @e5, @e23. Refs are stable across actions — use them to target clicks, fills, and scrolls. When an element leaves the DOM, its ref is never reused.

Refs resolve through a 3-tier system: backendNodeId (fast) → CSS domPath (fallback) → REF_STALE error.

Consequences

Every action returns what changed:

  • appeared — new interactive elements in the DOM

  • disappeared — elements that left the DOM

  • changed — elements with modified properties (name, value, checked, etc.)

  • network — Fetch/XHR requests triggered by the action

  • dom-churn — remove-then-re-add pairs (e.g. React re-rendering an entire list on scroll)

  • layout-shift — CLS events without recent user input

Scroll detection

browser_scroll detects rendering pathologies that are invisible to before/after snapshot diffing:

→ browser_scroll({ ref: "@e12", direction: "down", amount: "page" })

consequences: [
  { type: "dom-churn", churnCount: 36, desc: "DOM churn detected: 36 remove/re-add pairs" },
  { type: "layout-shift", cls: 0.042, shiftCount: 2, desc: "Layout shift: cls=0.042 (2 shifts)" }
]

Setup

npm install
npm run build

Usage

Launch Chrome automatically:

node dist/index.js

Connect to an existing Chrome instance:

node dist/index.js --cdp-url ws://127.0.0.1:9222/devtools/browser/...

With Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "browser-stream": {
      "command": "node",
      "args": ["/path/to/browser-stream/dist/index.js"]
    }
  }
}

Development

npm run dev          # watch mode build
npm test             # run tests
npm run test:watch   # watch mode tests

Architecture

src/
├── index.ts              # CLI entrypoint, MCP server setup
├── types.ts              # All shared types and response schemas
├── cdp/
│   └── client.ts         # CDP connection (chrome-launcher + chrome-remote-interface)
├── state/
│   ├── ref-map.ts        # @e ref registry with 3-tier resolution
│   ├── snapshot.ts       # AX tree → ref assignment → compact line format
│   └── differ.ts         # Pre/post snapshot diffing → consequences
├── actions/
│   ├── interactable.ts   # Scroll-into-view + box model + center point
│   ├── stability.ts      # DOM mutation debounce + network tracking + churn detection
│   └── engine.ts         # Action orchestration (click, fill, scroll, etc.)
└── tools/
    ├── actions.ts        # MCP tool registrations for actions
    └── observation.ts    # MCP tool registrations for snapshot/wait_for

License

MIT

Related MCP Connectors

Related MCP Servers

  • F
    license
    Not graded
    quality
    Not graded
    maintenance
    Enables AI agents to browse and interact with web pages through a persistent headless Chromium session, serving compact structured orientations, targeted element queries, and full detail only when explicitly requested. It supports navigation, observation, form filling, monitoring, and session management while cutting token overhead by up to ~140x versus raw accessibility-tree dumps.
    4 npm
    -
  • F
    license
    Not graded
    quality
    A
    maintenance
    Enables AI agents to browse and interact with websites through a persistent headless Chromium session, returning compact structured page representations instead of full accessibility-tree dumps. Agents can navigate, query specific elements and forms, click, type, manage tabs and cookies, and monitor console or network activity while paying a fraction of the tokens.
    4 npm
    -
  • F
    license
    Not graded
    quality
    A
    maintenance
    Enables AI agents to browse and interact with web pages through a token-efficient, structured page representation — orientation summaries, targeted element queries, and full detail only on request — instead of raw accessibility-tree dumps. Supports navigation, interaction, forms, screenshots, console and network monitoring, session/tab management, and browser-based development auditing.
    4 npm
    -
  • A
    license
    Not graded
    quality
    A
    maintenance
    Enables AI agents to browse the web through a persistent headless Chromium session that returns compact, structured page summaries and targeted queries instead of full accessibility-tree dumps. Agents can navigate, observe, search, and interact with pages using configurable detail levels and tool profiles, cutting token costs by up to ~140x on content-heavy sites.
    4 npm
    MIT