league-client-mcp: Instructions file for Codex

League Client MCP — Agent Instructions

Recognized by: OpenAI Codex CLI, OpenCode, Cursor, Windsurf, Aider, and any agent that reads AGENTS.md from the project root.

You are working with a live League of Legends Client via the league-client-mcp MCP server. The server bridges AI tool calls to a Pengu Loader plugin running inside the LoL Client (CEF/Chromium) over WebSocket at ws://127.0.0.1:8080.

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Architecture

AI Agent  ──MCP stdio──►  MCP Server (Node.js)
                               │  WebSocket ws://127.0.0.1:8080
                               ▼
                    Pengu Loader Plugin  (inside LoL Client)
                               │  DOM · CSS · JS · LCU fetch()
                               ▼
                    League of Legends Client  (CEF / Chromium / Ember.js)

Prerequisites: League of Legends must be running with Pengu Loader active. The plugin auto-connects on client load. All 16 tools will be unavailable until the plugin connects.

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Standard Workflow

1. get_lol_dom_snapshot      → map the current page (selectors, component hierarchy)
2. inject_lol_css            → prototype visual changes instantly (replaced on each call)
3. query_lol_element         → verify selector, computed style, or bounding rect
4. inject_lol_plugin         → add persistent JS behaviour with optional CSS
5. reload_lol_plugin         → iterate after updating code (teardown + re-execute)
6. export_plugin_to_pengu    → write finished plugin to disk as a Pengu Loader module
7. reload_lol_client         → activate the exported plugin permanently

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Tool Reference

DOM Inspection

get_lol_dom_snapshot

Returns a sanitized HTML snapshot of the active page. SVG path data, data-* attributes, inline event handlers, and long src/href values are stripped to keep output lean. Start every session here to discover selectors before writing any CSS or JS. No parameters.

query_lol_element

Returns tag, text content, bounding rect, and computed styles for one specific element. Use this when you already know the selector and just need to verify it — much faster than a full snapshot.