🔥 LEANN Claude Code Integration

Transform your development workflow with intelligent code assistance using LEANN's semantic search directly in Claude Code.

Prerequisites

Install LEANN globally for MCP integration (with default backend):

uv tool install leann-core --with leann

This installs the leann CLI into an isolated tool environment and includes both backends so leann build works out-of-the-box.

🚀 Quick Setup

Add the LEANN MCP server to Claude Code:

claude mcp add leann-server -- leann_mcp

🛠️ Available Tools

Once connected, you'll have access to these powerful semantic search tools in Claude Code:

leann_list - List all available indexes across your projects
leann_search - Perform semantic searches across code and documents
leann_ask - Ask natural language questions and get AI-powered answers from your codebase

🎯 Quick Start Example

# Build an index for your project (change to your actual path)
leann build my-project --docs ./

# Start Claude Code
claude

🚀 Advanced Usage Examples

Index Entire Git Repository

# Index all tracked files in your Git repository.
# Note: submodules are currently skipped; we can add them back if needed.
leann build my-repo --docs $(git ls-files) --embedding-mode sentence-transformers --embedding-model all-MiniLM-L6-v2 --backend hnsw

# Index only tracked Python files from Git.
leann build my-python-code --docs $(git ls-files "*.py") --embedding-mode sentence-transformers --embedding-model all-MiniLM-L6-v2 --backend hnsw

# If you encounter empty requests caused by empty files (e.g., __init__.py), exclude zero-byte files. thanks @ww2283 for pointing (that)[https://github.com/yichuan-w/LEANN/issues/48] out
leann build leann-prospec-lig --docs $(find ./src -name "*.py" -not -empty) --embedding-mode openai --embedding-model text-embedding-3-small

Multiple Directories and Files

# Index multiple directories
leann build my-codebase --docs ./src ./tests ./docs ./config --embedding-mode sentence-transformers --embedding-model all-MiniLM-L6-v2 --backend hnsw

# Mix files and directories
leann build my-project --docs ./README.md ./src/ ./package.json ./docs/ --embedding-mode sentence-transformers --embedding-model all-MiniLM-L6-v2 --backend hnsw

# Specific files only
leann build my-configs --docs ./tsconfig.json ./package.json ./webpack.config.js --embedding-mode sentence-transformers --embedding-model all-MiniLM-L6-v2 --backend hnsw

Advanced Git Integration

# Index recently modified files
leann build recent-changes --docs $(git diff --name-only HEAD~10..HEAD) --embedding-mode sentence-transformers --embedding-model all-MiniLM-L6-v2 --backend hnsw

# Index files matching pattern
leann build frontend --docs $(git ls-files "*.tsx" "*.ts" "*.jsx" "*.js") --embedding-mode sentence-transformers --embedding-model all-MiniLM-L6-v2 --backend hnsw

# Index documentation and config files
leann build docs-and-configs --docs $(git ls-files "*.md" "*.yml" "*.yaml" "*.json" "*.toml") --embedding-mode sentence-transformers --embedding-model all-MiniLM-L6-v2 --backend hnsw

Try this in Claude Code:

Help me understand this codebase. List available indexes and search for authentication patterns.

🧠 How It Works

The integration consists of three key components working seamlessly together:

leann - Core CLI tool for indexing and searching (installed globally via uv tool install)
leann_mcp - MCP server that wraps leann commands for Claude Code integration
Claude Code - Calls leann_mcp, which executes leann commands and returns intelligent results

📁 File Support

LEANN understands 30+ file types including:

Programming: Python, JavaScript, TypeScript, Java, Go, Rust, C++, C#
Data: SQL, YAML, JSON, CSV, XML
Documentation: Markdown, TXT, PDF
And many more!

💾 Storage & Organization

Project indexes: Stored in .leann/ directory (just like .git)
Global registry: Project tracking at ~/.leann/projects.json
Multi-project support: Switch between different codebases seamlessly
Portable: Transfer indexes between machines with minimal overhead

🗑️ Uninstalling

To remove the LEANN MCP server from Claude Code:

claude mcp remove leann-server

To remove LEANN

uv pip uninstall leann leann-backend-hnsw leann-core

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