Cal

Verified Integration

Author: @Timestamp•Category: ServerApplication

GitHub Repository

JSON-RPC 2.0

Protocol Standard

Sub-second

Execution Latency

Active

Operational Status

Client Configuration

— Connect Cal to Claude Desktop or Cursor in seconds

{
  "mcpServers": {
    "cal": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-cal"
      ],
      "env": {}
    }
  }
}

Paste into ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows).

Architecture & Capabilities

System Overview

Calculates mathematical expressions via a lightweight server.

Indexed Date

7/22/2026

License

Open Source

Protocol Layer

stdio / SSE RPC

Frequently Asked Questions

Architecture and operational details for Cal

Cal requires Bun as a runtime environment, FastMCP for building the server, `expr-eval` for expression parsing, and `zod` for parameter validation. It is highly recommended to use the latest version of Bun.

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