Calculator Agent — Development skill for Claude Code

calculator-agent

A conversational calculator that answers everyday math questions in plain English. Ask it to split a bill, add tax, compute percentages, or evaluate any arithmetic expression — it picks the right tool automatically and streams the answer back word-by-word.

Supports **Anthropic Claude** and **Google Gemini** out of the box via a clean provider abstraction — swap backends by changing one line.


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Features

• Natural language input — no need to type formulas; just ask
• Streaming responses — answers print word-by-word as the model generates them
• Pluggable LLM backend — switch between Claude and Gemini (or add any provider) without touching agent logic
• Four built-in tools the model calls automatically:
  • calculate — general arithmetic (sqrt, **, %, pi, e, parentheses)
  • percentage — "what is X% of Y?"
  • split_bill — divide a bill N ways with an optional tip
  • add_tax — apply a sales-tax rate to a subtotal
• Safe evaluator — arithmetic is parsed via Python's ast module, never eval()
• Session persistence — conversation history is saved to history.json and reloaded on next launch
• /history — replay the current session in the terminal
• /history export — export the session as a Markdown file

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Setup

Prerequisites

• Python 3.12+
• `uv` — fast Python package manager
• An API key for your chosen provider (Anthropic or Gemini)

Install

git clone https://github.com/tusharjayanti/calculator-agent.git
cd calculator-agent
uv sync

Configure

Copy `.env.example` to `.env` and fill in the key for the provider you want to use:

cp .env.example .env

# Anthropic — https://console.anthrop