fsb-mcp-server

library0.7.3jsnpmunverified

FSB MCP Server (v0.7.3) is a Node.js server that bridges the Model Context Protocol (MCP) to the FSB Chrome Extension, enabling AI agents (Claude, Cursor, Windsurf, etc.) to control a browser across four modes: manual, visual session, autopilot, and agent. Released under MIT license with active development (multiple releases per month), it offers 62+ tools for fine-grained browser automation, self-documenting tool descriptions, cookie consent auto-dismiss, site-aware search, and vault tools for secure credential access. Unlike Puppeteer-based solutions, it uses a Chrome extension for direct interaction with the user's existing browser session, preserving login state and avoiding remote debugging protocol complexities.

llm-agents testing devops

npm install fsb-mcp-server

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · FSB-MCP-SERVER

fsb-mcp-server

llm-agentsjavascriptv0.7.3

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

FSBServer

✓ import { FSBServer } from 'fsb-mcp-server'

✗ const FSBServer = require('fsb-mcp-server')

Package is ESM-only since v0.3.0. CommonJS require() will fail with ERR_REQUIRE_ESM.

createServer

✓ import { createServer } from 'fsb-mcp-server'

✗ import createServer from 'fsb-mcp-server'

createServer is a named export, not default. Default export is undefined.

FSBConfig

✓ import type { FSBConfig } from 'fsb-mcp-server'

✗ import { FSBConfig } from 'fsb-mcp-server'

FSBConfig is a TypeScript type-only export. Use import type to avoid runtime errors.

Creates and starts an MCP server connected to the FSB Chrome Extension via stdio or HTTP transport.

import { createServer } from 'fsb-mcp-server'; const server = createServer({ transport: 'stdio', port: 7225, httpPort: 7226, extensionUrl: 'ws://localhost:7225', }); await server.start(); console.log('FSB MCP Server running on stdio'); // Or with Streamable HTTP: // const httpServer = createServer({ transport: 'http', httpPort: 7226 }); // await httpServer.start(); // console.log('HTTP MCP endpoint at http://127.0.0.1:7226/mcp');

Debug

Known issues

breakingBreaking change: v0.3.0 switched from CommonJS to ESM-only exports. Requires Node >= 18 and "type": "module" in package.json, or use dynamic import().

fix

Update consuming projects to use ESM: add "type": "module" to package.json, or use import() instead of require().

affects: >=0.3.0

breakingBreaking change: v0.3.0 renamed the main export from McpServer to FSBServer; createServer() was introduced in v0.4.0 as the recommended way to instantiate.

fix

Use createServer() instead of new FSBServer(). FSBServer constructor is deprecated and may be removed.

affects: >=0.3.0 <0.4.0

deprecatedFSBServer constructor is deprecated since v0.4.0. Use createServer() factory function instead.

fix

Replace `new FSBServer(opts)` with `createServer(opts)`.

affects: >=0.4.0

gotchaThe default transport is stdio; to use HTTP/Streamable HTTP, you must explicitly set transport to 'http'. The httpPort option is ignored in stdio mode.

fix

Pass `transport: 'http'` and `httpPort: 7226` to createServer for HTTP mode.

affects: >=0.4.0

gotchaIf the FSB Chrome Extension is not installed or not connected, the server will start but all browser automation tools will fail with errors like 'Extension not connected'. The server does not auto-launch Chrome.

fix

Ensure the FSB Chrome Extension is installed and the browser is running before starting the MCP client.

affects: >=0.1.0

Errors

Common errors & fixes

Error [ERR_REQUIRE_ESM]: require() of ES Module /path/to/node_modules/fsb-mcp-server/dist/index.js from /path/to/your-project/app.js not supported. Instead change the require of index.js in /path/to/your-project/app.js to a dynamic import() which is available in all CommonJS modules.

Attempting to require() an ESM-only package from a CommonJS module.

fix

Use dynamic import: `const { createServer } = await import('fsb-mcp-server');` or switch your project to ESM by adding `"type": "module"` to package.json.

TypeError: server.start is not a function

Using the deprecated FSBServer constructor which no longer returns an object with .start() method, or calling .start() before the server is fully initialized.

fix

Use createServer() and await the promise: `const server = await createServer(opts); server.start();`

Error: Extension not connected. Please ensure the FSB Chrome Extension is installed and the browser is running.

The MCP server started but cannot communicate with the FSB browser extension.

fix

Install the FSB Chrome Extension from the GitHub repository, launch Chrome, and ensure the extension is active (check by navigating to chrome://extensions and verifying it is enabled).

Upgrade

Version history

0.7.3latest on npm

Audit

Dependencies

@modelcontextprotocol/sdkrequiredProvides the MCP server infrastructure and protocol handling for tool registration and transport.

puppeteer-coreoptionalOptional dependency for launching a separate Chrome instance if the extension is not available; fallback for headless scenarios.

Agent activity

29 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/lakshmanturlapati/FSB ↗

packagehttps://www.npmjs.com/package/fsb-mcp-server ↗

homepagehttps://fsb.space ↗