Module mcp 

MCP (Model Context Protocol) server for browser automation.

Exposes stygian-browser capabilities as an MCP server over stdin/stdout using the JSON-RPC 2.0 protocol. External tools (LLM agents, IDE plugins) can acquire browsers, navigate pages, evaluate JavaScript, and capture screenshots via the standardised MCP interface.

Enabling

[dependencies]
stygian-browser = { version = "*", features = ["mcp"] }

To use browser_attach (cdp_ws mode), also enable mcp-attach:

[dependencies]
stygian-browser = { version = "*", features = ["mcp", "mcp-attach"] }

Running the server

STYGIAN_MCP_ENABLED=true cargo run --example mcp_server -p stygian-browser

Protocol

The server implements MCP 2025-11-25 over JSON-RPC 2.0 on stdin/stdout. Supported methods:

MCP Method	Description
initialize	Handshake, return server capabilities
tools/list	List available browser tools
tools/call	Execute a browser tool
resources/list	List active browser sessions as MCP resources
resources/read	Read session state

Tools

Tool	Parameters	Returns
browser_acquire	stealth_level?, tls_profile?, webrtc_policy?, cdp_fix_mode?, proxy? (opt-in only)	session_id, requested_metadata
browser_acquire_and_extract	url, mode, wait_for_selector?, extraction_js?, total_timeout_secs?	strategy_used, final_url, status_code, extracted?, html_excerpt?, diagnostics
browser_navigate	session_id, url, timeout_secs?	title, url
browser_eval	session_id, script	result: Value
browser_screenshot	session_id	data: base64 PNG
browser_content	session_id	html: String
browser_attach (mcp-attach feature)	mode, endpoint?, profile_hint?, target_profile?	attach session result
browser_auth_session	session_id, mode, file_path?, ttl_secs?, navigate_to_origin?, interaction_level?	auth/session workflow result
browser_session_save	session_id, ttl_secs?, file_path?, include_snapshot?	saved session state metadata
browser_session_restore	session_id, snapshot?, file_path?, use_saved?, navigate_to_origin?	restored session state metadata
browser_apply_behavior_json	behavior, session_id?	applied behavior plan + effective config
browser_humanize	session_id, level?, viewport_width?, viewport_height?	humanization result
browser_verify_stealth	session_id, url, timeout_secs?	DiagnosticReport JSON
browser_release	session_id	success
pool_stats	–	active, max, available
browser_query	session_id, url, selector, fields?, limit?, timeout_secs?	results array of text or field objects
browser_extract	session_id, url, root_selector, schema, timeout_secs?	results array of structured objects
browser_extract_with_fallback	session_id, url, root_selectors, schema, timeout_secs?	first successful selector + results
browser_extract_resilient	session_id, url, root_selector, schema, timeout_secs?	results plus skipped-count metadata
browser_find_similar (similarity feature)	session_id, url, reference_selector, threshold?, max_results?, timeout_secs?	scored matches array
browser_warmup	session_id, url, wait?, timeout_ms?, stabilize_ms?	warmup report
browser_refresh	session_id, wait?, timeout_ms?, reset_connection?	refresh report

Proxy guidance: leave proxy unset by default. Only pass proxy when the user explicitly requests proxy routing or after a proxy has been acquired from the proxy pool.

Structs

JsonRpcError

A JSON-RPC 2.0 error object.

JsonRpcRequest

A JSON-RPC 2.0 request.

JsonRpcResponse

A JSON-RPC 2.0 response.

McpBrowserServer

Functions

is_mcp_enabled

Returns true if the MCP server is enabled via the STYGIAN_MCP_ENABLED environment variable.