Mnemosyne OS — Claude Code MCP server for local agent memory
Hooks Claude and other coding agents up to your Mnemosyne OS vaults, so the model keeps context across sessions. The memory stays on your own machine.
claude mcp add --env MNEMO_DEFAULT_VAULT=<MNEMO_DEFAULT_VAULT> --env MNEMO_VAULTS=<MNEMO_VAULTS> --env MNEMO_SDK_PORT=<MNEMO_SDK_PORT> --transport stdio mnemosyne-os -- npx -y @mnemosyne_os/mcpWhat Mnemosyne OS does
The @mnemosyne_os/mcp package runs a stdio MCP server that exposes your vaults to the agent. Claude, Codex or Cursor can then read notes you filed yourself, along with whatever other agents on the machine have written.
It sits between the IDE and the Mnemosyne OS engine. Three environment variables do the wiring: MNEMO_DEFAULT_VAULT for the main vault, MNEMO_VAULTS for the rest, and MNEMO_SDK_PORT for the SDK endpoint. Leave them out and the server has nothing to open.
The project is open-core, with a closed part, and some listed features are marked experimental. Launch goes through npx, so there is no separate package install step.
What it helps with
- let a coding agent read your personal notes from a local vault
- carry project context from one Claude session to the next
- share a single memory store between several agents on the machine
- index a
.claudeor.cursorfolder as a memory source - keep working notes off hosted services
Example prompts for the agent
- Connect my Mnemosyne OS vault and pull up what we decided about the database migration
- Show me the recent notes in the vault that other agents wrote
- Save a summary of this session to Mnemosyne OS memory
How to install Mnemosyne OS
Platform CLI
claude mcp add --env MNEMO_DEFAULT_VAULT=<MNEMO_DEFAULT_VAULT> --env MNEMO_VAULTS=<MNEMO_VAULTS> --env MNEMO_SDK_PORT=<MNEMO_SDK_PORT> --transport stdio mnemosyne-os -- npx -y @mnemosyne_os/mcpReplace <…> with your own values
Platform CLI
codex mcp add mnemosyne-os --env MNEMO_DEFAULT_VAULT=<MNEMO_DEFAULT_VAULT> --env MNEMO_VAULTS=<MNEMO_VAULTS> --env MNEMO_SDK_PORT=<MNEMO_SDK_PORT> -- npx -y @mnemosyne_os/mcpReplace <…> with your own values
Config file
{
"mcpServers": {
"mnemosyne-os": {
"command": "npx",
"args": [
"-y",
"@mnemosyne_os/mcp"
],
"env": {
"MNEMO_DEFAULT_VAULT": "<MNEMO_DEFAULT_VAULT>",
"MNEMO_VAULTS": "<MNEMO_VAULTS>",
"MNEMO_SDK_PORT": "<MNEMO_SDK_PORT>"
}
}
}
}Replace <…> with your own values
Config file
{
"servers": {
"mnemosyne-os": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@mnemosyne_os/mcp"
],
"env": {
"MNEMO_DEFAULT_VAULT": "<MNEMO_DEFAULT_VAULT>",
"MNEMO_VAULTS": "<MNEMO_VAULTS>",
"MNEMO_SDK_PORT": "<MNEMO_SDK_PORT>"
}
}
}
}Replace <…> with your own values
Platform CLI
gemini mcp add -e MNEMO_DEFAULT_VAULT=<MNEMO_DEFAULT_VAULT> -e MNEMO_VAULTS=<MNEMO_VAULTS> -e MNEMO_SDK_PORT=<MNEMO_SDK_PORT> mnemosyne-os npx -y @mnemosyne_os/mcpReplace <…> with your own values
Step by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about Mnemosyne OS
How do I install Mnemosyne OS in Claude Code?
Run claude mcp add mcp -- npx -y @mnemosyne_os/mcp. To pass the environment variables, use `claude mcp add --env MNEMO_DEFAULT_VAULT=<MNEMO_DEFAULT_VAULT> --env MNEMO_VAULTS=<MNEMO_VAULTS> --env MNEMO_SDK_PORT=<MNEMO_SDK_PORT> --transport stdio mnemosyne-os -- npx -y @mnemosyne_os/mcp`.
What does Mnemosyne OS do?
It connects your coding agent to local Mnemosyne OS vaults, so the agent can read your memory and notes left by other agents without sending them off the machine.
What do I need to configure?
Three environment variables: MNEMO_DEFAULT_VAULT, MNEMO_VAULTS and MNEMO_SDK_PORT. In the Cursor and GitHub Copilot configs they live in the env block.
