webcrawl-mcp

webcrawl-mcp

  

A lightweight MCP server that gives Claude Code (or any MCP client) the ability to scrape, search, map, and crawl the web — using free, open-source libraries. Firecrawl is supported as an optional fallback for JS-heavy sites when you have a key.

Why

Most scraping doesn't actually need a headless browser. trafilatura handles the ~80% case (articles, docs, blogs) locally, which is faster and keeps external API usage to a minimum. This server routes the easy stuff through local extraction and only falls back to Firecrawl when content quality is genuinely poor.

Tools

| Tool | Purpose | |------|---------| | webcrawl_scrape | Fetch a single URL → {content, source} (markdown + provenance) | | webcrawl_search | DuckDuckGo search (optionally scrape results, each with provenance) | | webcrawl_map | Discover same-domain URLs from a starting page | | webcrawl_crawl | BFS crawl multiple pages (each result includes provenance) |

The source field on scraped content is one of static_http, static_http_retry, firecrawl_transport_fallback, or firecrawl_quality_fallback — see Fallback behavior.

Install

pip install webcrawl-mcp

Requires Python 3.12+.

Quick smoke test (should print Webcrawl MCP server running then exit cleanly with Ctrl-C):

webcrawl-mcp

Install from source (for development)

git clone https://github.com/andyliszewski/webcrawl-mcp.git
cd webcrawl-mcp
python -m venv venv
source venv/bin/activate      # Windows: venv\Scripts\activate
pip install -e .

Configure your MCP client

Claude Code

Create .mcp.json in your project root (or merge into ~/.claude/settings.json):

{
  "mcpServers": {
    "webcrawl": {
      "command": "uvx",
      "args": ["webcrawl-mcp"]
    }
  }
}

This uses uvx to run the package in a temporary environment — no manual install needed. If uvx is unavailable, install via pip install webcrawl-mcp and use "command": "webcrawl-mcp" with no args instead.

For a source checkout (development), point command at your venv's Python and use "args": ["-m", "webcrawl_mcp"].

Then in a Claude Code session run /mcp — you should see webcrawl listed with four tools.

Claude Desktop

Same JSON shape, placed in claude_desktop_config.json (see Anthropic's docs for the OS-specific path). Restart Claude Desktop after editing.

Other MCP clients (Cursor, Cline, Continue, Zed, etc.)

The command / args / env shape is standardized. Consult your client's MCP docs for where to put it.

Verify it's working

Ask your agent something like:

Use the webcrawl_scrape tool to fetch https://docs.python.org/3/library/asyncio.html and summarize the first section.

You should see the tool invocation in the client UI, followed by a summary grounded in the live page content. If nothing happens, see Troubleshooting.

Environment variables

All optional:

| Variable | Default | Purpose | |----------|---------|---------| | USER_AGENT | Mozilla/5.0 (compatible; WebcrawlMCP/1.0; …) | HTTP User-Agent | | REQUEST_TIMEOUT | 30 | Seconds before request timeout | | FIRECRAWL_API_KEY | (unset) | If set, enables Firecrawl fallback for low-quality extractions. Leave unset for a fully free setup. | | FIRECRAWL_API_URL | https://api.firecrawl.dev/v1 | Firecrawl endpoint | | FALLBACK_ON_TRANSPORT_ERROR | false | If true and FIRECRAWL_API_KEY is set, route bot-blocked statuses (403, 429, 503) to Firecrawl instead of raising. Opt-in. | | POLITE_MODE | true | On a 429 with a parseable Retry-After, retry the original request once after the indicated wait (capped at REQUEST_TIMEOUT) before falling through. |

Set these inside the env block of your MCP config, not in your shell — MCP servers run under the client, not your terminal.

Fallback behavior

The scraper distinguishes extraction-quality failure from transport failure and reports which path produced the content via the source field.

Extraction-quality path (default):

1. trafilatura extracts main content from HTML → source: static_http.
2. If that fails or returns <200 chars, markdownify converts the raw HTML.
3. If the result is still low-quality and FIRECRAWL_API_KEY is set, Firecrawl is used as a last resort → source: firecrawl_quality_fallback.

Transport path (opt-in):

If a request returns 403, 429, or 503 (typical bot-blocking responses):

• With POLITE_MODE=true (default), a 429 carrying a Retry-After header gets one bounded retry of the original request → source: static_http_retry on success.
• With FALLBACK_ON_TRANSPORT_ERROR=true and FIRECRAWL_API_KEY set, the request routes to Firecrawl instead of raising → source: firecrawl_transport_fallback.
• Otherwise, the transport error is raised to the caller (current behavior).

Without a Firecrawl key, the tool is fully self-contained and free; FALLBACK_ON_TRANSPORT_ERROR is a no-op without a key.

Troubleshooting

Client doesn't list webcrawl under MCP servers. The command path is almost always the problem. It must be an absolute path to the Python binary inside your venv, not just python. Test it in a terminal: /path/you/configured -m webcrawl_mcp should print Webcrawl MCP server running.

ModuleNotFoundError: webcrawl_mcp. Either pip install -e . didn't run in the same venv as command, or PYTHONPATH is missing/wrong. Double-check both point at the same checkout.

Python version mismatch. Requires 3.12+. python --version inside your venv should report ≥ 3.12. If not, recreate the venv with a newer Python.

Scrapes return very little text. Some sites render with JavaScript and can't be extracted statically. Either set FIRECRAWL_API_KEY to enable the fallback path, or accept that this tool isn't the right fit for that specific site.

Search is slow or rate-limited. DuckDuckGo throttles bursty querying. Space out searches, or reduce num_results.

Responsible use

This tool is for fetching public web content for research, coding assistance, and similar legitimate uses. You are responsible for:

• Respecting each target site's Terms of Service and robots.txt.
• Not overloading servers — the built-in per-domain rate limiter helps, but don't circumvent it.
• Complying with applicable laws around automated access and data use in your jurisdiction.

License

MIT — see LICENSE.

Acknowledgements

Built on top of trafilatura, httpx, beautifulsoup4, markdownify, ddgs, and fastmcp. Firecrawl integration uses the public Firecrawl API (not affiliated).