Second Brain

What it does

Second Brain is a local-first knowledge base that integrates your notes, transcripts, Slack, and Gmail into a queryable vault. It uses a hybrid search (FTS + vector) and an entity graph (GraphRAG) to provide AI agents with highly relevant, ranked snippets of your personal data without overloading the context window.

Tools

• brain search: Performs hybrid FTS and vector search across the knowledge base.
• brain show: Retrieves the full body of a specific document by ID.
• brain ingest: Adds new files (PDF, MD, DOCX) or directories to the brain.
• brain tag: Manages metadata tags for documents to improve organization.
• brain list: Browses ingested content filtered by source.

Installation

Add the following to your claude_desktop_config.json:

{
  "mcpServers": {
    "brain": {
      "command": "brain-mcp",
      "env": {
        "DATABASE_URL": "postgresql://brain:brain@localhost:55432/second_brain",
        "BRAIN_EMBEDDER": "arctic"
      }
    }
  }
}

Supported hosts

• Claude