voidcrawl-mcp 0.4.1

Stdio MCP server for stealthy headless Chrome via voidcrawl — expose the voidcrawl Chrome pool to Claude Code

voidcrawl-mcp

Rust-native MCP server that exposes void_crawl_core's stealth-patched Chrome pool to Claude Code. Headless by default, concurrent by construction — ten tabs in parallel is the norm.

Why not claude-in-chrome?

• claude-in-chrome drives the user's single visible Chrome tab.
• voidcrawl-mcp drives a headless pool with real concurrency and per-session isolation. Pick it for bulk scraping, bot-detection targets, and subagent fan-out. See ../../.claude/skills/voidcrawl/SKILL.md for the full decision rubric.

Tools

Tool	Kind	Summary
fetch	stateless	Single URL → { html, title, status_code, ... }.
fetch_many	stateless	N URLs in parallel; pool semaphore caps concurrency.
screenshot	stateless	Full-page PNG as image/png content.
session_open	stateful	Launches a dedicated Chrome, returns session_id.
session_navigate	stateful	Goto URL within a session and wait for settle.
session_content	stateful	HTML + title + URL of the session's current page.
session_close	stateful	Shut down the session's Chrome.
pool_status	diag	Pool config + live session count.
download	stateless	Download a file by URL through stealth Chrome and scan it with the built-in antivirus gate. Opt-in (VOIDCRAWL_ALLOW_DOWNLOADS=1).
download_arm / download_wait	stateful	Capture a download started by a page action (button with no stable URL), then scan it. Opt-in (VOIDCRAWL_ALLOW_DOWNLOADS=1).

This is an abbreviated list; the perceive/act tools (click, click_by_role, type_text, eval_js, extract, session_ax_tree, detect_captcha, …) are documented in the published MCP and File Downloads guides.

Each tool accepts a wait_for string: "networkidle" (default), "selector:<css>", or "ms:<n>".

Install

Repo-local (dev)

The repo ships an ../../.mcp.json at the root that runs the server via cargo run. Claude Code will pick it up automatically when launched from the repo.

Global

cargo install --path .
claude mcp add voidcrawl voidcrawl-mcp -e BROWSER_COUNT=1 -e TABS_PER_BROWSER=5

Configuration (environment)

All knobs are read by BrowserPool::from_env() in void_crawl_core:

Env var	Default	Meaning
BROWSER_COUNT	1	Number of Chrome processes to launch.
TABS_PER_BROWSER	4	Tabs per Chrome. max_tabs = BROWSER_COUNT * this.
TAB_MAX_USES	50	Hard-recycle a tab after this many acquires.
TAB_MAX_IDLE_SECS	60	Evict a tab after this many seconds idle.
ACQUIRE_TIMEOUT_SECS	30	Max wait for a free tab. 0 = infinite.
CHROME_HEADLESS	1	1 headless, 0 headful.
CHROME_NO_SANDBOX	0	1 to pass --no-sandbox (Docker/CI).
CHROME_WS_URLS	—	Comma-separated CDP WS endpoints to connect to instead of launching.
VIEWPORT_WIDTH	1920	Stealth viewport width.
VIEWPORT_HEIGHT	1080	Stealth viewport height.
CDP_PORT_BASE	—	Pin Chrome's --remote-debugging-port for launched browsers (browser i gets base + i). Unset = OS picks a free ephemeral port, which can't conflict. Set when a firewall only exposes specific ports.

One capability knob is read separately from from_env():

Env var	Default	Meaning
VOIDCRAWL_ALLOW_DOWNLOADS	unset (off)	1 exposes the download / download_arm / download_wait tools. Off by default: downloads pull untrusted bytes to disk over a live auth session, so they're opt-in.

Logging goes to stderr (RUST_LOG=voidcrawl_mcp=debug for more). stdout is reserved for the MCP protocol.

Protocol

Transport: stdio. Protocol version: whatever rmcp 1.4 defaults to.