ABOUTME: Documentation for McMaster-Carr MCP server.

ABOUTME: Covers installation, configuration, and usage.

McMaster-Carr MCP Server

MCP server for searching and looking up product information from McMaster-Carr.

Uses SeleniumBase UC mode to extract product data from JavaScript-rendered pages.

Features

• Product Lookup: Get detailed specs (10-35+ fields) for any McMaster-Carr part number

• Search: Search for products and get part numbers from results

• URL Generation: Generate McMaster URLs without fetching (fast, no browser)

• Cookie Persistence: Browser profile saved for faster subsequent requests

Related MCP server: Nexar MCP Server

Installation

cd tools/mcmaster-mcp
python -m venv .venv
source .venv/bin/activate
pip install -e .

Or install dependencies directly:

pip install mcp seleniumbase beautifulsoup4

Usage

Run the server directly

python server.py

Claude Code configuration

Add to ~/.claude.json (or your MCP config):

{
  "mcpServers": {
    "mcmaster-carr": {
      "command": "python",
      "args": ["/path/to/radiatron/tools/mcmaster-mcp/server.py"]
    }
  }
}

Available Tools

mcmaster_get_product

Get detailed product information by part number.

Input:

{
  "part_number": "47865K23"
}

Returns:

• Product name

• 10-35+ specifications (material, size, pressure ratings, thread type, etc.)

• URL to product page

Example output:

{
  "part_number": "47865K23",
  "name": "Brass Body On/Off Valve, with Lever Handle, 1/2 NPT Female, 32.3 Cv",
  "url": "https://www.mcmaster.com/47865K23",
  "specs": {
    "Pipe Size": "1/2",
    "Flow Coefficient (Cv)": "32.3",
    "Maximum Pressure": "600 psi @ 100° F",
    "Body Material": "Brass",
    "Valve Type": "Ball",
    "Thread Type": "NPT"
  }
}

mcmaster_search

Search McMaster-Carr and get products matching the query.

The search automatically navigates through McMaster's category structure to find actual product listings with part numbers and names.

Input:

{
  "query": "ball valve brass"
}

Returns: List of products with part numbers and names (up to 50).

{
  "query": "ball valve brass",
  "count": 22,
  "results": [
    {"part_number": "47865K23", "name": "Threaded On/Off Valves", "url": "..."},
    {"part_number": "4373K53", "name": "Diverting Valves", "url": "..."},
    {"part_number": "8151N11", "name": "Socket-Connect On/Off Valves", "url": "..."}
  ]
}

mcmaster_url

Generate McMaster URLs without fetching. Fast, no browser needed.

Input (product):

{
  "part_number": "47865K19"
}

Input (search):

{
  "search_query": "stainless steel bolt"
}

How It Works

1. SeleniumBase UC Mode - Undetected Chromium driver bypasses bot detection

2. Visible Browser - McMaster blocks headless browsers, so a Chrome window briefly appears

3. Cookie Persistence - Browser profile saved to ~/.mcmaster-browser for faster subsequent requests

4. BeautifulSoup - Parses spec tables from rendered HTML

Limitations

• Visible browser window: McMaster detects headless browsers, so a Chrome window briefly appears during requests

• First request slower: ~5-8 seconds for browser startup, subsequent requests ~3-5 seconds

• CSS class changes: May break if McMaster updates their class naming conventions

Files

• server.py - MCP server entry point

• browser.py - SeleniumBase browser automation

• agent.py - Product search agent with requirement parsing (CLI tool)

• mcmaster.py - Legacy CDP-mode client (deprecated, kept for reference)

Development

Run tests:

python test_agent.py
python test_search.py

Test the browser directly:

python -c "from browser import McMasterBrowser; b = McMasterBrowser(); b.start(); print(b.get_product('47865K23'))"