Calc

You can run Calc MCP to provide reliable, locally computed math, randomization, encoding, and date utilities to your AI assistant or MCP client. It runs entirely on your machine, sandboxed and private, so you get deterministic results without sending data to external services. This MCP server exposes a broad set of tools that your AI or client can call to perform exact calculations and related operations.

How to use

You will run Calc MCP as a local server that communicates with your MCP client over stdio. Start the server once, and then configure your MCP client to point to the local process. Your client can send requests to perform precise math, number base conversions, encoding, cryptographic hashes, date calculations, random values, and more. The server is designed to be deterministic and private: the same input yields the same output, and all computation happens locally on your machine.

How to install

Prerequisites: ensure you have Node.js installed on your system (version 14 or newer is recommended). You do not need an API key or external account to run Calc MCP itself.

Install and start Calc MCP using the runtime command shown in the quick-start flow. The server runs via an MCP-compatible client by invoking the package with npx.

# Start Calc MCP directly via npx (stdio mode)
npx --prefix /tmp -y @coo-quack/calc-mcp@latest

# Alternative: configure a client (e.g., Claude Desktop, Cursor, Windsurf) to use the same runtime
# Example client config snippet
{ 
  "mcpServers": {
    "calc-mcp": {
      "command": "npx",
      "args": ["--prefix", "/tmp", "-y", "@coo-quack/calc-mcp@latest"]
    }
  }
}

Configuration with MCP clients

If you are using Claude Code, Claude Desktop, Cursor, Windsurf, or VS Code Copilot, add Calc MCP as an MCP server with the same runtime details shown above. The server speaks over stdio, so your client should be configured to start the process and communicate through standard input and output.

Notes for usage

• The server does not require an API key. - All computations are performed locally. - For production secrets or sensitive data, prefer local-only LLMs or process outside MCP if you need extra security.

All 21 tools

Calc MCP exposes a suite of tools you can call from your MCP client. These tools cover mathematics, encoding, date and time handling, parsing, and more. Below are the tool names and concise descriptions.

Examples of tool usage

You can ask natural language questions and your MCP client will route them to the appropriate tool. For instance, you can request a precise numeric calculation, a base conversion, a cryptographic hash, or a date calculation. The tools are designed to be deterministic, private, and fast.

Security and privacy

Calc MCP processes all data locally and does not send data to external servers. When used with an LLM, inputs may be sent to the LLM provider unless you use a local LLM. Guard against sending production secrets to MCP tools through external services.

Available tools

math

Evaluate expressions, perform arithmetic, and compute statistics with deterministic results.

count

Count characters (grapheme-aware), words, lines, and bytes.

datetime

Get the current time, convert time zones, and handle timestamps.

random

Generate UUIDs (v4/v7), ULIDs, passwords with custom character sets, and shuffle arrays.

hash

Compute common hashes such as MD5, SHA-1, SHA-256, SHA-512, CRC32, and HMAC.

base64

Encode and decode data using Base64.

encode

URL-encode, HTML entity encode, and Unicode escape sequences.

date

Compute date differences, add/subtract days, and handle weekdays and wareki.

regex

Test, match, and replace using regular expressions.

base

Convert numbers between bases 2 through 36.

diff

Compute line diffs and Levenshtein distance.

json_validate

Validate JSON, CSV, XML, and YAML content.

cron_parse

Parse human-readable cron expressions and compute next runs.

luhn

Validate or generate Luhn check digits.

ip

Inspect IPv4/IPv6 addresses and compute CIDR ranges.

color

Convert between HEX, RGB, and HSL color formats (with alpha).

convert

Convert across categories like length, weight, temperature, area, volume, speed, and data.

char_info

Display Unicode code point, block, and category information.

jwt_decode

Decode JWT headers and payloads (without verification).

url_parse

Parse URLs into components like protocol, host, path, and query.

semver

Compare, validate, parse, and check version ranges.