Callosium

Callosium runs locally from a Node.js package published to the npm registry: callosium version 0.1.18. It speaks MCP over stdio, so the client starts it as a program and talks to it through standard input and output. It needs Node.js; clients usually start it with npx — the usual command is npx -y callosium@0.1.18. It reads the environment variable CALLOSIUM_MODEL_DIR; set it in the client's configuration for this server. Required arguments: --brain, --agent and --token.

In the mcpServers JSON format that many desktop and editor MCP clients read, the entry looks like this (placeholders in angle brackets):

{
  "mcpServers": {
    "callosium": {
      "command": "npx",
      "args": [
        "-y",
        "callosium@0.1.18"
      ],
      "env": {
        "CALLOSIUM_MODEL_DIR": "<value>"
      }
    }
  }
}

Derived from the registry entry, not tested here. What the server does, and on what terms, is set by its publisher; check its repository or website before giving it access to your accounts or files. How to add an MCP server to an assistant · Before you connect