Local Knowledge RAG MCP Server

A semantic search and retrieval system for local documents using vector embeddings. Powered by MCP (Model Context Protocol).

This project is based on the RAG implementation from Obsidian Smart Composer. We've adapted it to focus on local document search and knowledge management as a standalone MCP server.

Provides semantic search across your local documents using vector embeddings and similarity search, with support for multiple embedding providers (OpenAI, Ollama, and OpenAI-compatible APIs).

Overview

Local Knowledge RAG MCP Server enables AI-powered semantic search of your local document collections. Rather than keyword-based search, it understands the meaning of your queries and finds relevant content through vector embeddings.

Key capabilities:

• Semantic search powered by vector embeddings
• Support for multiple embedding providers (OpenAI, Ollama, LiteLLM, and any OpenAI-compatible APIs)
• Session-based search result caching
• Customizable report generation with multiple templates
• PostgreSQL with pgvector for high-performance vector similarity search
• HNSW indexing for fast approximate nearest neighbor search
• Incremental indexing and full rebuilds

Why This Project?

While experimenting with various RAG (Retrieval-Augmented Generation) solutions like Dify and RAGFlow, we encountered several limitations:

1. High Knowledge Base Management Cost: Adding, removing, and updating documents required time-consuming manual steps
2. Poor Citation Usability: Citations referenced internal knowledge base resources rather than actual source files, making them difficult to work with
3. Limited Output Format Flexibility: Report generation was rigid and couldn't be easily customized

Obsidian Smart Composer solved problems #1 and #2 beautifully by working directly with your local files. This inspired us to bring that same experience to VS Code, where many developers spend most of their time.

What makes Local Knowledge RAG MCP Server unique:

• Flexible Report Templates: Customize RAG output format freely with template files (unlike rigid output formats in other solutions)
• Scalable to Large Knowledge Bases: Uses PostgreSQL's pgvector extension for efficient vector similarity search, handling large document collections
• Built-in Index Manager: Web-based interface for monitoring indexing progress and managing your knowledge base
• VS Code Integration: Seamless integration with Claude Code extension, bringing RAG capabilities directly into your development workflow

Recommended Environment

This MCP server is optimized for the following environment:

• IDE: VS Code
• Extension: Claude Code for VS Code
• AI Model: Claude Sonnet 4.5 (latest)

While the server works with any MCP-compatible client, the above combination provides the best experience with optimal performance and integration.

Quick Start

Get up and running in 5 steps:

1. Set up PostgreSQL with pgvector

Using Docker (easiest):

docker run -d \
  --name local-knowledge-rag-db \
  -e POSTGRES_DB=local_knowledge_rag \
  -e POSTGRES_USER=user \
  -e POSTGRES_PASSWORD=password \
  -p 5432:5432 \
  -v local-knowledge-rag-data:/var/lib/postgresql/data \
  --restart unless-stopped \
  ankane/pgvector

Note: The credentials above are for local development only. If port 5432 is already in use, change the host port (e.g., -p 5433:5432) and update DATABASE_URL accordingly.

2. Clone and build the project

git clone https://github.com/patakuti/local-knowledge-rag-mcp.git
cd local-knowledge-rag-mcp
npm install
npm run build

3. Configure environment variables

# Copy the example file
cp .env.example .env

# Edit .env with your settings
# Minimal configuration:
DATABASE_URL=postgresql://user:password@localhost:5432/local_knowledge_rag

# Choose ONE embedding provider:
# Option A: OpenAI
OPENAI_API_KEY=sk-your-openai-api-key

# Option B: LiteLLM (recommended - supports multiple providers)
OPENAI_COMPATIBLE_BASE_URL=http://localhost:4000/v1
OPENAI_COMPATIBLE_API_KEY=your-litellm-key
EMBEDDING_MODEL=cl-nagoya/ruri-v3-310m

# Option C: Ollama (local, offline)
OLLAMA_BASE_URL=http://localhost:11434/v1
EMBEDDING_MODEL=nomic-embed-text

4. Add to Claude Code

Add this MCP server to Claude Code:

# Add globally (available in all projects)
claude mcp add -s user local-knowledge-rag -- node /path/to/local-knowledge-rag-mcp/dist/mcp-server.js

# Add to a specific project
cd /path/to/your/project
claude mcp add local-knowledge-rag -- node /path/to/local-knowledge-rag-mcp/dist/mcp-server.js

Note: Environment variables are loaded from .env file automatically. Do not add them to MCP server configuration for security reasons.

5. Start using it!

Restart Claude Code and start a conversation:

1. Open Index Manager: Say to Claude: "Open the Index Manager"
2. Build Index: In the web interface that opens, click "Update Index" button
3. Start Searching: Say to Claude: "Search my documents for information about [your topic] and create a report"

That's it! Claude will use the RAG tools automatically to search your documents and generate reports.

See Usage Examples for more details.

Features

• Semantic Search: Uses vector embeddings to find semantically similar content
• Multiple Embedding Providers: OpenAI, Ollama, or any OpenAI-compatible API
• Multi-Workspace Support: Use the same database for multiple independent workspaces
• Session Management: Cache and reuse search results across multiple queries
• Template-Driven Reports: Generate formatted Markdown reports with customizable templates
• pgvector Extension: High-performance vector similarity search with PostgreSQL
• HNSW Indexing: Fast approximate nearest neighbor search for large datasets
• Flexible File Patterns: Include/exclude file patterns for fine-grained control
• MCP Integration: Seamless integration with Claude Code and other MCP clients
• Real-time Progress Tracking: Web-based progress viewer showing live updates during index operations with percentage completion, file count, and current file being processed

Configuration

All configuration is done via environment variables in a .env file. See Quick Start for basic setup.

Common configuration tasks:

• Changing embedding models: Edit .env, run reload_config tool, then rebuild index
• Adjusting search parameters: Edit .env RAG settings, restart MCP server
• File patterns: Edit RAG_INCLUDE_PATTERNS and RAG_EXCLUDE_PATTERNS in .env

For complete configuration reference, see [docs/configuration.md](docs/configuration.md).

Multi-Workspace Support

Multiple workspaces can share the same PostgreSQL database. Each workspace automatically maintains its own isolated index based on its absolute path.

Key Features:

• ✅ Multiple workspaces share the same DATABASE_URL (configured in .env)
• ✅ Each workspace has its own isolated index (no data conflicts)
• ✅ Concurrent updates are safe (protected by PostgreSQL advisory locks)

Just use the same database for all your projects - the system handles workspace isolation automatically.

Usage Examples

Creating the Index

Before you can search, you need to create an index of your documents:

1. Say to Claude: "Open the Index Manager"
2. In the web interface, click the "Update Index" button to index your documents
3. Wait for indexing to complete - you'll see real-time progress in the interface

Note: The Index Manager will only index files matching your patterns (default: **/*.md and **/*.txt). You can change these patterns in your .env file.

Searching Your Documents

Once your index is ready, just talk to Claude naturally:

Simple search:

• "Search my documents for information about React hooks and create a report"
• "Find documentation about database setup and create a summary"
• "Look for examples of error handling and create a report"

Search in specific folders:

• "Search the /src/components folder for button implementations and create a report"
• "Find configuration examples in the docs directory and create a summary"

Advanced analysis:

• "Search for React patterns and create a detailed summary report"
• "Analyze my database schema and generate documentation"

Claude will automatically:

1. Search your indexed documents
2. Find relevant content based on semantic similarity
3. Generate a formatted Markdown report
4. Save the report to ./rag-reports/ directory

Advanced: For direct MCP tool usage and detailed parameters, see docs/mcp-tools.md.

Report customization: Reports are saved to ./rag-reports/ by default. You can create custom templates (built-in: basic, paper, bullet_points, manual) - see docs/templates.md.

Available MCP Tools

Search & Reports:

• search_knowledge - Perform semantic search
• get_search_results - Retrieve detailed results
• create_rag_report - Generate Markdown reports
• list_search_results - List cached sessions

Indexing:

• rebuild_index - Rebuild document index
• cancel_index_generation - Cancel indexing
• index_status - Check index status

Management:

• reload_config - Reload .env configuration
• open_index_manager - Open web UI
• reinitialize_schema - Reset workspace (⚠️ destructive)

For detailed parameters and examples, see [docs/mcp-tools.md](docs/mcp-tools.md).

Index Manager

Web-based interface for monitoring indexing progress and managing your knowledge base. Runs as an independent process on localhost:3456 (or next available port).

Access: Say to Claude "Open the Index Manager" or use open_index_manager tool

Features: Real-time progress tracking, project statistics, index operations (update/rebuild/cancel)

Logs: /tmp/local-knowledge-rag-mcp/{workspaceId}/index-manager.log

CLI Tool (lkrag)

A command-line interface for index management and search, suitable for cron jobs, editor integrations, and automation.

Installation

After building the project, install globally or use via npx:

npm run build
npm link   # makes lkrag available in PATH

Commands

lkrag search <query>       Search indexed documents
lkrag update-index         Incrementally update the index
lkrag rebuild-index        Rebuild the entire index from scratch
lkrag status               Show index status

Options

Examples

# Search with plain output
lkrag search "authentication flow" --workspace-path /path/to/docs

# Search from a subdirectory — finds the nearest indexed ancestor automatically
lkrag search "error handling" --find-workspace

# TSV output for editor integration (path, line, score, content)
lkrag search "setup guide" --format tsv --limit 10

# JSON output for scripting
lkrag search "database schema" --format json | jq '.[0].path'

# Update index from a subdirectory
lkrag update-index --find-workspace

# Schedule index updates via cron (daily at 3am)
# 0 3 * * * node /path/to/dist/cli.js update-index --workspace-path /path/to/docs

# Check index status
lkrag status

Emacs Integration Example

Results are displayed in a persistent *rag-results* buffer.

;;; lkrag integration

(defvar rag-workspace-path nil
  "Explicit lkrag workspace path.
When nil (default), --find-workspace is used to locate the nearest
indexed ancestor directory automatically.
Example: (setq rag-workspace-path \"~/etc/txt/myproject/\")")

(defvar rag-results-mode-map
  (let ((map (make-sparse-keymap)))
    (define-key map (kbd "n")   #'rag-results-next)
    (define-key map (kbd "p")   #'rag-results-prev)
    (define-key map (kbd "RET") #'rag-results-open)
    (define-key map (kbd ".")   #'rag-results-open-other-window)
    (define-key map (kbd ",")   #'rag-results-close)
    (define-key map (kbd "q")   #'quit-window)
    map))

(define-derived-mode rag-results-mode special-mode "RAG"
  "Major mode for lkrag search results.
\\{rag-results-mode-map}")

(defun rag-results--loc ()
  "Return (path . line) for the result at point, or nil."
  (get-text-property (line-beginning-position) 'rag-location))

(defun rag-results--preview ()
  "Show file at point in other window; focus stays on results buffer."
  (when-let ((loc (rag-results--loc)))
    (save-selected-window
      (find-file-other-window (car loc))
      (goto-line (cdr loc))
      (recenter))))

(defun rag-results-open ()
  "Open result at point full-screen."
  (interactive)
  (when-let ((loc (rag-results--loc)))
    (find-file-other-window (car loc))
    (goto-line (cdr loc))
    (recenter)
    (delete-other-windows)))

(defun rag-results-open-other-window ()
  "Open result at point in other window; focus stays on results buffer."
  (interactive)
  (when-let ((loc (rag-results--loc)))
    (save-selected-window
      (find-file-other-window (car loc))
      (goto-line (cdr loc))
      (recenter))))

(defun rag-results-close ()
  "Kill the buffer visiting the file at point."
  (interactive)
  (when-let ((loc (rag-results--loc)))
    (when-let ((buf (find-buffer-visiting (car loc))))
      (kill-buffer buf))))

(defun rag-results-next ()
  "Move to the next result and preview it."
  (interactive)
  (let ((pos (save-excursion
               (forward-line 1)
               (while (and (not (eobp)) (null (rag-results--loc)))
                 (forward-line 1))
               (and (rag-results--loc) (point)))))
    (when pos
      (goto-char pos)
      (rag-results--preview))))

(defun rag-results-prev ()
  "Move to the previous result and preview it."
  (interactive)
  (let ((pos (save-excursion
               (forward-line -1)
               (while (and (not (bobp)) (null (rag-results--loc)))
                 (forward-line -1))
               (and (rag-results--loc) (point)))))
    (when pos
      (goto-char pos)
      (rag-results--preview))))

(defun rag-search (query)
  "Search lkrag index and display results in *rag-results* buffer."
  (interactive "sSearch: ")
  (let* ((explicit-workspace (and rag-workspace-path
                                  (expand-file-name rag-workspace-path)))
         (current-dir (expand-file-name default-directory))
         (lkrag (or (executable-find "lkrag")
                    (expand-file-name "~/.npm-global/bin/lkrag")))
         (stderr-file (make-temp-file "lkrag-stderr"))
         (cmd (if explicit-workspace
                  (format "%s search %s --format tsv --limit 50 --quiet --workspace-path %s 2>%s"
                          lkrag
                          (shell-quote-argument query)
                          (shell-quote-argument explicit-workspace)
                          (shell-quote-argument stderr-file))
                (format "%s search %s --format tsv --limit 50 --find-workspace 2>%s"
                        lkrag
                        (shell-quote-argument query)
                        (shell-quote-argument stderr-file))))
         (output (shell-command-to-string cmd))
         (stderr (prog1 (with-temp-buffer
                          (insert-file-contents stderr-file)
                          (buffer-string))
                   (delete-file stderr-file)))
         (found-workspace (when (string-match "^\\[lkrag\\] workspace: \\(.*\\)" stderr)
                            (match-string 1 stderr)))
         ;; When --find-workspace returned a parent of current-dir, filter to current-dir
         (filter-to-current (and (null explicit-workspace)
                                 found-workspace
                                 (not (string= (file-truename found-workspace)
                                               (file-truename current-dir)))))
         ;; expand-root: workspace root used to resolve lkrag's relative paths
         ;; display-root: shown in From: header and used for file-relative-name
         (expand-root (or explicit-workspace found-workspace current-dir))
         (display-root (if filter-to-current current-dir expand-root))
         (all-tsv-lines (seq-filter (lambda (l) (string-match-p "\t" l))
                                    (split-string (string-trim output) "\n" t)))
         (tsv-lines (if filter-to-current
                        (seq-filter
                         (lambda (line)
                           (let* ((parts (split-string line "\t"))
                                  (path (expand-file-name (nth 0 parts) expand-root)))
                             (string-prefix-p (file-truename current-dir)
                                              (file-truename path))))
                         all-tsv-lines)
                      all-tsv-lines))
         (buf (get-buffer-create "*rag-results*")))
    (with-current-buffer buf
      (let ((inhibit-read-only t))
        (erase-buffer)
        (rag-results-mode)
        (insert (propertize (format "Search: %s\n" query) 'face 'bold))
        (insert (propertize (format "From:   %s\n\n" display-root) 'face 'shadow))
        (if (null tsv-lines)
            (insert "No results found.\n")
          (dolist (line tsv-lines)
            (let* ((parts   (split-string line "\t"))
                   (path    (expand-file-name (nth 0 parts) expand-root))
                   (lineno  (string-to-number (nth 1 parts)))
                   (score   (nth 2 parts))
                   (content (nth 3 parts))
                   (relpath (file-relative-name path display-root))
                   (excerpt (truncate-string-to-width content 60))
                   (start   (point)))
              (insert (propertize relpath 'face 'compilation-info)
                      (propertize (format ":%d" lineno) 'face 'compilation-line-number)
                      (propertize (format " [%s] " score) 'face 'shadow)
                      excerpt "\n")
              (put-text-property start (point) 'rag-location (cons path lineno)))))
        (goto-char (point-min))
        (forward-line 3)))
    (pop-to-buffer buf)
    (rag-results--preview)))

;; Optional key binding
;; (global-set-key (kbd "C-c r") #'rag-search)

Notes:

• rag-workspace-path — set only when the indexed root differs from the directory you work in. When nil, --find-workspace locates the nearest indexed ancestor automatically.
• When --find-workspace is used, lkrag prints the resolved workspace path to stderr ([lkrag] workspace: /path/to/ws). The Emacs integration captures this via a temp file to display the correct From: path and compute relative paths accurately.
• When --find-workspace resolves to a parent of default-directory (i.e. the current directory is not itself indexed), results are automatically filtered to files under default-directory. The search fetches 50 candidates upfront to leave enough headroom after filtering. From: and relative paths are shown relative to default-directory in this case.
• expand-file-name ensures ~ is resolved before passing to the shell, avoiding single-quote quoting issues.
• The *rag-results* buffer persists across searches; each new search overwrites it.

VS Code Integration Example

A minimal VS Code extension is included in vscode-extension/. It opens a QuickPick search panel where results are previewed as you navigate, and Enter opens the selected file at the matching line.

Installation

# From the repo root — link or copy into VS Code's extensions directory
ln -s "$(pwd)/vscode-extension" ~/.vscode/extensions/lkrag-search-0.1.0
# Then reload VS Code (Developer: Reload Window)

Alternatively, package as a .vsix and install via the Extensions sidebar:

npm install -g @vscode/vsce
cd vscode-extension
vsce package          # produces lkrag-search-0.1.0.vsix
# Extensions sidebar → ⋯ → Install from VSIX…

Usage

Open the Command Palette (Ctrl+Shift+P / Cmd+Shift+P) and run lkrag: Search.

• Type a query — results appear after a short debounce
• Arrow keys move through results; the file is previewed in the editor
• Enter opens the selected file at the matching line
• Escape cancels

Keybinding (optional)

Add to keybindings.json (Ctrl+Shift+P → "Open Keyboard Shortcuts (JSON)"):

{ "key": "ctrl+alt+r", "command": "lkrag.search" }

Settings

Notes:

• lkrag.workspacePath — set only when the indexed root differs from the directory you work in. When empty, --find-workspace locates the nearest indexed ancestor automatically.
• The extension has no npm dependencies; no npm install is required before use.
• The VS Code extension host inherits PATH from the environment VS Code was launched in. If lkrag is not found, set lkrag.executablePath explicitly.

Index Update Behavior

• If an Index Manager server is running for the workspace, update-index and rebuild-index delegate to it via HTTP (non-blocking).
• If no server is running, the CLI runs the operation directly with progress output to stderr.

Troubleshooting

Documents not being indexed

1. Check logs: /tmp/local-knowledge-rag-mcp/{workspaceId}/index-manager.log
2. Verify .env configuration (DATABASE_URL, API keys)
3. Check file patterns: RAG_INCLUDE_PATTERNS and RAG_EXCLUDE_PATTERNS

No search results

• Try different search terms or lower similarity threshold
• Verify indexing completed: use index_status tool
• Rebuild index if needed

API errors

• Verify API key is valid and has correct permissions
• Check rate limits (switch to Ollama if needed)

Switching embedding models

1. Edit .env with new model settings
2. Run reload_config tool
3. Run rebuild_index with reindex_all: true

For complete troubleshooting guide, see [docs/troubleshooting.md](docs/troubleshooting.md).

Security

API Key Management

• Never commit API keys to version control
• Use .env files locally and .env.example in the repository
• Rotate keys regularly
• Use environment-specific keys when possible

Network Security

• Index Manager (Web UI): Binds to 127.0.0.1:3456 (loopback only) without authentication
• Not accessible from external networks by default
• Designed for trusted local development environments only

Local Data Handling

• All documents are processed locally by default
• Embeddings are stored in PostgreSQL database
• Progress logs are stored in system temporary directory
• Ensure proper database access control and backup
• Database connections should only be allowed from trusted networks

Best Practices

• Review .gitignore to ensure sensitive files are excluded
• For sensitive data, consider using Ollama for fully offline, local processing
• Regularly rotate API keys and monitor API usage for unusual patterns

Contributing

Contributions are welcome! Please see CONTRIBUTING.md for guidelines.

Note: This project is maintained on a limited-time basis. PR reviews may take several weeks. Security issues are prioritized.

License

MIT License - see LICENSE for details.

Credits

• Obsidian Smart Composer - Original RAG implementation
• Model Context Protocol (MCP)
• Claude Code