Claude Desktop and the aletheia MCP server

Claude Desktop speaks MCP over stdio. Aletheia's server is bin/mcp.mjs; one JSON entry under mcpServers is all it needs. No hook and no rules file exist for Claude Desktop, so this page is setup only.

Config file location

OS	Path	Source
macOS	`~/Library/Application Support/Claude/claude_desktop_config.json`	MCP quickstart, fetched 2026-10-26
Windows	`%APPDATA%\Claude\claude_desktop_config.json`	MCP quickstart, fetched 2026-10-26
Linux	`~/.config/Claude/claude_desktop_config.json`	UNVERIFIED: the file exists on this machine, but the MCP quickstart does not name a Linux path

Source: https://modelcontextprotocol.io/quickstart/user (fetched 2026-10-26).

The entry

Use an absolute Bun path and an absolute path to bin/mcp.mjs:

{
  "mcpServers": {
    "aletheia": {
      "command": "/absolute/path/to/bun",
      "args": ["/absolute/path/to/aletheia-mem/bin/mcp.mjs"],
      "env": {}
    }
  }
}

aletheia is the server name. The store path comes from ALETHEIA_HUB_DB; set it in env if the default <data dir>/hub.db is not what you want.

Merge, never replace

The config file already holds Claude Desktop preferences and other MCP servers. Aletheia only adds or removes mcpServers.aletheia; everything else is kept byte-for-byte apart from JSON formatting. Running the merge twice is a no-op, and a changed file gets a .aletheia-bak-<timestamp> copy first. An unparsable file is refused.

What was and was not tested

The merge and the generated JSON are tested against fixtures (test/claude-desktop.test.mjs).
Claude Desktop was not opened with this config here. docs/manual-test.md records the manual step.

Restart

Quit Claude Desktop completely and reopen it. The server appears under the hammer/tools icon. If it does not, run the command from the entry by hand and read its stderr.