@memorycrystal/mcp-server

Persistent memory for AI assistants via the Model Context Protocol.

Install

npm install -g @memorycrystal/mcp-server

Configure

Set environment variables:

• CRYSTAL_API_KEY — your Memory Crystal API key (get it at memorycrystal.ai/dashboard)
• CRYSTAL_SITE — optional, defaults to https://rightful-mockingbird-389.convex.site

Claude Desktop

Add to ~/.claude/claude_desktop_config.json:

{
  "mcpServers": {
    "memory-crystal": {
      "command": "crystal-mcp",
      "env": {
        "CRYSTAL_API_KEY": "your-api-key-here"
      }
    }
  }
}

Claude Code

Add to .claude/mcp.json in your project:

{
  "mcpServers": {
    "memory-crystal": {
      "command": "crystal-mcp",
      "env": {
        "CRYSTAL_API_KEY": "your-api-key-here"
      }
    }
  }
}

Or run directly:

CRYSTAL_API_KEY=your-key crystal-mcp

Codex

Add to your Codex MCP config or pass via environment:

CRYSTAL_API_KEY=your-key npx @memorycrystal/mcp-server

Available Tools

| Tool | Description | |------|-------------| | crystal_wake | Get a contextual briefing at session start | | crystal_remember | Save a memory (decision, lesson, goal, etc.) | | crystal_recall | Semantic search across your memories | | crystal_recent | Get recently accessed memories | | crystal_search_messages | Search conversation history | | crystal_what_do_i_know | Summarize what's known about a topic | | crystal_why_did_we | Explain the reasoning behind past decisions | | crystal_checkpoint | Save a session checkpoint | | crystal_forget | Archive (soft-delete) a memory | | crystal_stats | Get memory usage stats |

Memory Stores

• sensory — immediate context, fades fastest
• episodic — events and conversations
• semantic — facts and knowledge
• procedural — how-to knowledge and workflows
• prospective — goals and future intentions

Memory Categories

decision · lesson · person · rule · event · fact · goal · workflow · conversation