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MCP Currency Converter in Claude Code

ECB reference rates with the rate date on every answer. It caches the European Central Bank's daily and historical euro reference rates, converts between any currencies the ECB quotes through EUR cross rates, and emits the exact fx_rates object the expense tracker needs to rebill a project in one currency.

The whole chain lives in one terminal session: expense_to_invoice to see which currencies are present, fx_rates_for to fetch them, expense_to_invoice again with the rates, invoice_create to issue. Nobody types an exchange rate.

What you get in Claude Code

You say	Tool
What is 4,500 EUR in USD today?	`convert`
What was the GBP rate on 30 August?	`rate_on`
Rebill Nova in USD using today's rates.	`fx_rates_for then expense_to_invoice`

Counted from the published history file: the ECB series runs 1999-01-04 to 2026-09-02, 10,104 calendar days holding 7,084 dates, so 29.9% of dates carry no rate. Every answer names the rate date it actually used.

Install it in Claude Code

The file is .mcp.json, and the key inside it is mcpServers.

Scope	Path
local (default)	`~/.claude.json, this project only`
project	`.mcp.json at the repository root`
user	`~/.claude.json, every project`

claude mcp add currency -- npx -y @theluckystrike/mcp-currency
claude mcp list    # health-check it before the first prompt

# or --scope project, committed to .mcp.json for the team

No restart. The entry is picked up in the next session, and `/mcp` reconnects one on demand.

The npm publish of @theluckystrike/mcp-currency is pending; until then use the .mcpb bundle or a clone and build from the latest release.

No install: the hosted endpoint

There is no hosted endpoint for this one yet. MCP Currency Converter runs locally over stdio with the config above, which is also the only form in which it reads and writes files on your own disk. Three of the servers in this collection are served at https://mcp.zovo.one/mcp/<name> over MCP streamable HTTP: time-tracker, price-tracker and invoice.

Claude Code notes worth knowing first

The `--` is load-bearing: it separates Claude Code's own options, such as --transport, --env and --scope, from the command that runs the server. And the default scope is local, private to you and to the directory you ran it in, so adding it in the wrong folder leaves the tools absent with no error at all.

Free: latest rates, convert, convert_many, fx_rates_for, history windows up to 90 days. Pro is $19 once, verified offline.

Questions

Which scope should I use for MCP Currency Converter?

Local, the default, writes ~/.claude.json and is private to you and that directory. --scope project writes .mcp.json at the repository root, shared through version control. --scope user loads it everywhere.

Why did my first prompt ignore the server?

Measured, not documented: of three fresh projects, one first prompt made zero tool calls although initialize answered in 1.05 seconds. Run claude mcp list once first: it prints Connected, and the next run used the tool.

Can I use MCP Currency Converter without installing anything?

Not yet. MCP Currency Converter runs locally over stdio, which is also how it reads and writes files on your disk. The hosted endpoints at https://mcp.zovo.one/mcp currently cover time-tracker, price-tracker and invoice.

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