leankg-rule

leankg-rule is a cursor rule for Cursor from FreePeak/LeanKG. It costs 0 tokens per session (424 once invoked), scanned A, original, Apache-2.0.

A rule that makes LeanKG the default way to search and navigate source code, with several fallback methods.

In plain words
What is it for?
Use it to find symbols and files, inspect dependencies and callers, understand context, and measure the likely impact of a file change.
Why use it?
It prevents the agent from skipping the project's structured code index when one is available.

Cursor rule for Cursor

Written for Cursor: a Cursor plugin manifest.

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/freepeak/leankg/leankg-rule
Clone the repo
git clone --depth 1 https://github.com/FreePeak/LeanKG

Made for: Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for leankg-rule

README.md
[![agentmods](https://agentmods.dev/badge/rules/freepeak/leankg/leankg-rule.svg)](https://agentmods.dev/rules/freepeak/leankg/leankg-rule)
Your own site
<a href="https://agentmods.dev/rules/freepeak/leankg/leankg-rule"><img src="https://agentmods.dev/badge/rules/freepeak/leankg/leankg-rule.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 424 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00000 $0.00424
Opus 5 $0.00000 $0.00212
Sonnet 5 $0.00000 $0.00085
Haiku 4.5 $0.00000 $0.00042

Measured 6d ago against content hash d31023352212, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

leankg-rule scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.cursor-plugin/rules/leankg-rule.mdc · 46 lines

What it actually says

LeanKG Mandatory Rule

MANDATORY 4-Tier Search Fallback Chain

Tier 1: LeanKG MCP (mcp_status → search_code / find_function / query_file)
Tier 2: leankg CLI (leankg query "X" --kind name)
Tier 3: rtk (rtk grep "X" --path .)
Tier 4: grep/rg (LAST RESORT)

LeanKG MCP Tools

  1. mcp_status - Check readiness first
  2. search_code("X") - Find by name/type
  3. find_function("X") - Function definitions
  4. query_file("*X*") - Files by name
  5. get_impact_radius(file) - Change impact
  6. get_context(file) - Read content
  7. get_dependencies(file) - Imports
  8. get_dependents(file) - Reverse deps
  9. get_callers("func") - Who calls
  10. get_call_graph("func") - Full graph

ABSOLUTE BANS

  • NEVER skip to grep when LeanKG available
  • NEVER use Glob before LeanKG for code
  • ONLY exception: non-code files (config, docs)
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 46 lines · 0 tokens per session scan A d31023352212

Subscribe to this mod's changes

leankg-rule is a cursor rule published in the GitHub repository FreePeak/LeanKG (216 stars, last pushed today), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 424 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.