league-client-mcp: Instructions file for Gemini CLI

League Client MCP — Gemini CLI Instructions

Gemini CLI loads this file automatically when you run gemini in this directory.

You are working with a live League of Legends Client via the league-client-mcp MCP server. The server bridges 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

Gemini CLI  ──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)

League must be running with Pengu Loader active. The plugin auto-connects on client load.

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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 (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
6. export_plugin_to_pengu    → write finished plugin to disk
7. reload_lol_client         → activate the exported plugin permanently

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Tool Reference

DOM Inspection

get_lol_dom_snapshot — Sanitized HTML snapshot of the active page. SVG paths, data-* attrs, inline handlers, and long src/href values are stripped. Start every session here. No parameters.

query_lol_element — Tag, text, bounding rect, and computed styles for a single element.

Parameter	Type	Description
selector	string	CSS selector
index	number?	Which match (default 0)
attributes	string[]?	Extra attributes to read

CSS & JavaScript

inject_lol_css — Replaces the global <style> tag. Use !important on all rules.