How to use the Currency and Number Formatting Review agent skill

What the currency-formatting skill makes the agent do

Number and currency formatting differs across locales. The same amount that reads "$1,234.56" in the US is written "1.234,56 $" in Germany and "¥1,235" in Japan. Hardcoded formatting shows the wrong output to international users and becomes harder to maintain as you add locales.

With the skill installed, the agent looks at utility functions, component props and template strings that display numbers, prices, percentages or dates. It flags hardcoded currency symbols, separators and date format strings, and suggests replacements using Intl.NumberFormat, Intl.DateTimeFormat and Intl.Collator. It also flags locale-sensitive sorting that uses plain string comparison.

• Flags manual currency symbols such as fixed $ signs
• Flags manual thousands separators such as commas
• Flags hardcoded date format strings
• Suggests Intl.NumberFormat with the currency style for money
• Suggests Intl.DateTimeFormat for dates and times
• Suggests Intl.Collator for sorting and searching
• Flags formatters that have no fallback locale

Install the currency-formatting skill

Download the skill ZIP from this page and unzip it. You can install it in one of two places. For a personal setup, unzip it into ~/.claude/skills/. For a single project, unzip it into the project's .claude/skills/ folder.

If you use the Claude apps, you can instead upload the skill under Settings → Capabilities → Skills.

• Personal: ~/.claude/skills/
• Project only: .claude/skills/ inside your project
• Claude apps: Settings → Capabilities → Skills, then upload

Know what the skill contains

The skill folder contains two files. SKILL.md holds the skill's name, its description and the review steps the agent follows: Check, Fix, Explain and Code Review. references/rule.md holds fuller implementation details and code examples, which the agent can read when it needs more depth.

• SKILL.md: name, description and review steps
• references/rule.md: full details and code examples

Trigger the skill with natural requests

The skill's description says it applies when reviewing utility functions, component props or template strings that format numbers, prices or dates. You don't need special syntax. Ask in plain language about the code you want reviewed, and mention the kind of formatting you care about.

Point the agent at specific files or folders where possible, so the review stays focused on the code that renders values to users.

• "Review src/utils/format.ts for hardcoded currency formatting."
• "Check our product price components for places that should use Intl.NumberFormat."
• "Find date formatting in these templates that ignores the user's locale."
• "Look for string-based sorting of customer names that should use Intl.Collator."

Example: replacing a hardcoded price format

A typical finding is a helper that adds a $ sign and inserts commas by hand. The skill's fix is to use Intl.NumberFormat with style set to currency and a currency code, and to pass the user's locale explicitly. The formatter then handles symbol placement, decimal digits and grouping for each locale.

The reference file includes a formatCurrency example for this pattern. Check the reference file for the exact code before you copy it into your project.

Safety notes and what the skill needs

According to the skill's listing, it requires nothing beyond the agent itself. It does not run scripts and does not use the network. It only reads and suggests changes to the code you give it. Review any suggested edits before applying them, as you would with any code change.

The skill covers display formatting only. It does not decide rounding or precision rules, so it is not a substitute for review of back-end financial or accounting logic.

• Requires: nothing listed
• Runs scripts: no
• Uses network: no
• Licence: MIT