dayone

The Day One MCP Server exposes Day One journal operations as MCP tools that can be invoked by AI assistants via JSON-RPC over stdio. It supports listing journals with access enabled, creating and updating journal entries with markdown content, performing full-text searches, and retrieving or filtering entries by date or journal. This enables AI workflows to programmatically manage Day One content without leaving the local environment. Clients communicate by sending JSON-RPC requests to the server's stdio interface and receive JSON-RPC responses in return.

You can load and configure the server in your MCP client (e.g., Claude Desktop, Claude Code CLI, Cursor, or other stdio-based clients). Typical usage involves starting the server via the Day One CLI (dayone mcp) and then invoking tools like list_journals, create_entry, get_entries, and update_entry through the client’s tool-cublishing or call mechanisms. Ensure that the Day One journals you want to access have MCP access enabled in Day One’s preferences for security and privacy.

Prerequisites

• macOS with Day One for Mac installed
• Day One CLI (the dayone command) available in your PATH

Step 1: Install Day One for Mac

• Open the Mac App Store and install Day One for Mac.

Step 2: Install Day One CLI

• Run the following to install the dayone CLI tool:

sudo bash /Applications/Day\ One.app/Contents/Resources/install_cli.sh

• This installs the dayone command to /usr/local/bin/dayone.
• Verify installation:

/usr/local/bin/dayone --version

Step 3: Start using the MCP server

• The MCP server runs as a stdio-based process via the Day One CLI:

/usr/local/bin/dayone mcp

Step 4: Configure MCP client

• For Claude Desktop: download the latest .mcpb bundle from Releases and install via Settings > Extensions.
• For Claude Code CLI: run

claude mcp add --scope user --transport stdio dayone-cli /usr/local/bin/dayone mcp

• For Cursor: edit ~/.cursor/mcp.json to include the dayone-cli entry as demonstrated in the README.
• For manual configuration in other MCP clients, configure with:
  • command: /usr/local/bin/dayone
  • args: ["mcp"]
  • transport: stdio

Step 5: Configure Journal Access

• Open Day One and go to Preferences → Labs.
• Enable "Mac CLI MCP Server" and use "MCP Access Control" to select journals to expose.
• Only enabled journals will be accessible to AI assistants.

Notes and tips:

• This MCP server operates entirely locally; there is no network I/O in the server process. However, MCP clients may send retrieved content to remote LLM APIs for processing.
• Security is enforced at the journal level via Day One's access controls. Make sure you explicitly enable journals you want accessible.
• If you encounter issues starting the server, ensure the Day One CLI is correctly installed and that the journals you want are enabled for MCP access.
• The server uses JSON-RPC 2.0 over stdio; consult your MCP client documentation for exact request/response formatting and how to invoke tools such as list_journals, create_entry, get_entries, and update_entry.