21 MCP tools for math, randomness, dates, encoding, hashing, and more — deterministic and accurate.
Quick Install
Automated & IDE SetupCopy the AI prompt to install this server into Claude Code, Cursor, or another agent — or use 1-click editor setup below.
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Manual Client & Custom JSON ConfigExpand JSON ▾
Client Config & Setup
Choose your client or environment
Target File:
💡 Paste the JSON block into your client's configuration file under mcpServers, then restart the application.
Documentation Overview
Calc MCP
📖 Documentation — Full tool reference, examples, and install guides.
21 tools for things AI is not good at — deterministic math, cryptographic randomness, accurate date arithmetic, encoding, hashing, and more.
LLMs hallucinate calculations, can't generate true random numbers, and struggle with timezones. This MCP server fixes that.
Quick Start
Works with Claude Desktop, VS Code Copilot, Cursor, Windsurf, and any MCP client — setup guides below.
Why?
| AI alone | With calc-mcp |
|---|---|
| "10 + 34 × 341 ÷ 23 = 507.8" ❌ | 514.087 ✅ (math) |
| "Here's a UUID: 550e8400-..." 🤷 fake | Cryptographically random UUID v4/v7 ✅ (random) |
| "100 days from now is..." 🤔 guess | 2026-05-22 ✅ (date) |
| "SHA-256 of password123 is..." 💀 hallucinated | {"hash": "ef92b778bafe..."} ✅ (hash) |
- Deterministic — Same input, same correct output, every time
- Secure — Sandboxed math, ReDoS protection, weak hash warnings
- Private — All computation runs locally, no data sent to external services
- No server config — Install once via npx; MCP client setup required
- No API key — No account or API key required for calc-mcp itself; requires Node.js
Examples
Ask in natural language — your AI assistant selects the appropriate tool.
Math & Numbers
| You ask | You get | Tool |
|---|---|---|
| What's 10 + 34 × 341 ÷ 23? | 514.087 | math |
| Convert 255 to binary | 11111111 | base |
| Is 4539578763621486 a valid card number? | true | luhn |
Text & Encoding
| You ask | You get | Tool |
|---|---|---|
| How many characters in "Hello, World! 🌍"? | 15 chars, 18 bytes | count |
| Base64 encode "Hello World" | SGVsbG8gV29ybGQ= | base64 |
| Base64 decode "eyJhbGciOiJIUzI1NiJ9" | {"alg":"HS256"} | base64 |
| URL-encode "hello world" | hello%20world | encode |
| URL-decode "hello%20world" | hello world | encode |
HTML-decode <script> | <script> | encode |
| SHA-256 hash of "password123" | {"hash": "ef92b778bafe..."} | hash |
| HMAC-SHA256 of "message" with key "secret" | {"hash": "8b5f48702995..."} | hash |
Date & Time
| You ask | You get | Tool |
|---|---|---|
| What time is it in New York? | 2026-02-10T19:00:00-05:00 | datetime |
| What's 100 days after 2026-02-11? | 2026-05-22 | date |
| When does "30 9 * * 1-5" run? | Mon–Fri at 9:30 | cron_parse |
Generation
| You ask | You get | Tool |
|---|---|---|
| Generate a UUID v7 | 019c4b54-aad2-7e52-... | random |
| Generate a readable 20-char password | hT9jZDojX6sHRJt8vaKS | random |
| Shuffle ["Alice", "Bob", "Charlie"] | ["Charlie", "Alice", "Bob"] | random |
Conversion
| You ask | You get | Tool |
|---|---|---|
| 100 miles in kilometers? | 160.93 km | convert |
| 72°F in Celsius? | 22.22°C | convert |
| Convert #FF5733 to RGB | rgb(255, 87, 51) | color |
| Convert rgba(255, 0, 0, 0.5) to 8-digit HEX | #ff000080 | color |
Analysis & Parsing
| You ask | You get | Tool |
|---|---|---|
| Extract numbers from "abc123def456" | 123, 456 | regex |
| Does 1.5.3 satisfy ^1.0.0? | true | semver |
| Does 1.8.0 satisfy ">=1.5.0 <2.0.0"? | true | semver |
| IP range of 192.168.1.0/24? | 192.168.1.1 – .254 (254 hosts) | ip |
| Edit distance: "kitten" → "sitting" | 3 | diff |
| Unicode info for "€" | U+20AC, Currency Symbols | char_info |
Is {"name":"test"} valid JSON? | valid, object | format_validate |
Decode & Parse
| You ask | You get | Tool |
|---|---|---|
| Decode this JWT: eyJhbGci... | { alg: "HS256", name: "John Doe" } | jwt_decode |
| Parse https://example.com/search?q=hello | host: example.com, q: "hello" | url_parse |
All 21 Tools
| Tool | Description |
|---|---|
math | Evaluate expressions, statistics |
count | Characters (grapheme-aware), words, lines, bytes |
datetime | Current time, timezone conversion, UNIX timestamps |
random | UUID v4/v7, ULID, passwords (readable, custom charset), random number, shuffle |
hash | MD5, SHA-1, SHA-256, SHA-512, CRC32, HMAC |
base64 | Encode / decode |
encode | URL, HTML entity, Unicode escape |
date | Diff, add/subtract, weekday, wareki |
regex | Test, match, matchAll, replace |
base | Number base conversion (2–36) |
diff | Line diff, Levenshtein distance |
format_validate | Validate JSON, CSV, XML, YAML |
cron_parse | Human-readable cron + next runs (weekday/month names supported) |
luhn | Validate / generate check digits |
ip | IPv4/IPv6 info, CIDR contains check, range calculation |
color | HEX ↔ RGB ↔ HSL (alpha channel supported) |
convert | 8 categories, 146 unit names: length, weight, temperature, area (tsubo, tatami), volume, speed, data, time |
char_info | Unicode code point, block, category |
jwt_decode | Decode header + payload (no verification) |
url_parse | Protocol, host, path, params, hash |
semver | Compare, validate, parse, range satisfaction |
Install
Claude Code
Claude Code plugin
Also available as a plugin from the coo-quack marketplace:
See the installation guide for details.
Claude Desktop / Cursor / Windsurf
Add to your config file:
| App | Config path |
|---|---|
| Claude Desktop (macOS) | ~/Library/Application Support/Claude/claude_desktop_config.json |
| Claude Desktop (Windows) | %APPDATA%\Claude\claude_desktop_config.json |
| Cursor | ~/.cursor/mcp.json |
| Windsurf | ~/.codeium/windsurf/mcp_config.json |
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