Xe

An MCP server for the Xe Currency Data API — brings live FX rates, historical analysis, and quant-flavored tools directly into Claude Code, Claude Desktop, and any MCP-compatible AI tool.

Works out of the box with zero credentials — falls back to Frankfurter (ECB data) automatically. Plug in Xe API keys to switch to Xe's live data. All 12 tools work without credentials.

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Tools

Tool	What it does
get_rate	Live mid-market rate between any two currencies
convert	Convert an amount at the current rate
list_currencies	Common currencies (built-in); full Xe list (~170 currencies) with Xe key
get_historical_rates	Daily rates for a currency pair over N days
volatility_analysis	Daily std-dev + annualised vol — log-return methodology (FX options standard)
optimal_send_window	Percentile rank of today's rate in the N-day distribution + verdict
nzd_corridors	NZD snapshot across USD, AUD, EUR, GBP, JPY, SGD, CNY in one call
correlation_analysis	Pearson r of daily log-returns between two currency pairs
rate_alert_check	Check if a rate has crossed a threshold — returns triggered: YES/NO + distance
rate_chart	ASCII line chart of a currency pair's rate history in the terminal
moving_average	SMA(20/50/200) with current rate and % distance from each average
pair_summary	One-call morning briefing: rate + range + vol + send verdict + SMA(20)

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Live output examples

All examples below use Frankfurter/ECB — no API key required.

> get_rate NZD USD
1 NZD = 0.564940 USD (Frankfurter/ECB, 2026-06-26)

> optimal_send_window NZD USD
NZD→USD send window (Frankfurter/ECB)
Current rate:  0.564940
30-day mean:   0.580598
30-day range:  0.563860 – 0.597400
Percentile:    14th (3/21 historical days were lower)
Verdict:       UNFAVOURABLE — bottom quartile
Timestamp:     2026-06-26

> moving_average NZD USD
NZD/USD — moving averages (Frankfurter/ECB)
Current rate: 0.564940

SMA(20):  0.579758  (current is 2.56% below)
SMA(50):  insufficient data (need 50 days, have 36)

> volatility_analysis NZD USD 30
NZD/USD — 30-day volatility (Frankfurter/ECB)
Current rate:       0.564940
Range (30d):        0.563860 – 0.597400
Daily volatility:   0.4023%
Annualised vol:     6.39%
Data points used:   21

> correlation_analysis NZD USD AUD USD 30
Correlation: NZD/USD vs AUD/USD (Frankfurter/ECB, 30d)
Pearson r:       0.8553
Interpretation:  strong positive
Data points:     20 aligned trading days

> rate_chart NZD USD 30
NZD/USD — last 30 trading days (Frankfurter/ECB)
  0.5974 │●●               
         │  ●●             
         │    ●●●          
         │       ●●        
  0.5806 │         ●●│   │ 
         │               ●●│
         │                 ●│
         │                  ●│
  0.5639 │                   ●●●
         └─────────────────────
          05-29     06-12  06-26

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Setup

Zero-credential mode (Frankfurter/ECB)

All 11 tools work with no API keys using free ECB data via Frankfurter. list_currencies returns a built-in common currency list; with Xe credentials it returns the full ~170 currency list.

git clone https://github.com/CedricConday/xe-mcp
cd xe-mcp
npm install && npm run build

Add to Claude Code:

claude mcp add xe-mcp node /path/to/xe-mcp/dist/index.js

With Xe API (live rates)

Get credentials at xe.com/xecurrencydata, then:

claude mcp add xe-mcp node /path/to/xe-mcp/dist/index.js \
  -e XE_ACCOUNT_ID=your_account_id \
  -e XE_API_KEY=your_api_key

Or add to .claude/settings.json:

{
  "mcpServers": {
    "xe-mcp": {
      "command": "node",
      "args": ["/path/to/xe-mcp/dist/index.js"],
      "env": {
        "XE_ACCOUNT_ID": "your_account_id",
        "XE_API_KEY": "your_api_key"
      }
    }
  }
}

Claude Code slash command

This repo ships a /fx command for quick analysis. Add it to your project:

cp -r .claude/commands /your-project/.claude/

Then use /fx NZDUSD, /fx NZDUSD vol, /fx convert 1000 NZD USD.

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Architecture

Local (MCP stdio server)

Claude Code ↔ stdio ↔ xe-mcp ──→ Xe XECD API (if credentialed)
                                └→ Frankfurter/ECB (free fallback)

xe-mcp/
├── src/
│   ├── index.ts              # MCP server (stdio transport)
│   ├── xe-client.ts          # Xe XECD API wrapper (authenticated)
│   ├── frankfurter-client.ts # Frankfurter ECB API (free fallback)
│   ├── s3-cache.ts           # S3-backed rate history cache (Lambda use)
│   └── tools/
│       ├── rates.ts          # get_rate, convert, list_currencies
│       ├── analysis.ts       # get_historical_rates, volatility_analysis, optimal_send_window
│       ├── nzd.ts            # nzd_corridors
│       ├── correlation.ts    # correlation_analysis
│       ├── alerts.ts         # rate_alert_check
│       └── chart.ts          # rate_chart (ASCII)
├── lambda/
│   ├── handler.ts            # REST Lambda — all 10 tools via POST /tool/{name}
│   ├── alert-scheduler.ts    # CloudWatch hourly → DynamoDB scan → SQS publish
│   └── alert-processor.ts    # SQS consumer → SES email notification
├── src/__tests__/            # 49 unit tests (5 suites)
├── .github/workflows/
│   ├── ci.yml                # Test → Build → verify on push
│   └── deploy.yml            # Test → Build → SAM deploy to AWS (ap-southeast-2)
├── Dockerfile                # Multi-stage Alpine — local & ECS/K8s deployments
└── template.yml              # SAM: Lambda + API Gateway + SQS + DynamoDB + S3

AWS deployment (sam deploy)

API Gateway → handler Lambda → Xe/Frankfurter → response
CloudWatch Events (hourly) → alert-scheduler Lambda → DynamoDB → SQS
                                                                  ↓
                                                     alert-processor Lambda → SES email
DynamoDB: alert configurations (userId, from, to, threshold, direction)
S3: rate-history cache bucket (scaffolded in src/s3-cache.ts; not yet wired into the handler)

Credential detection: XE_ACCOUNT_ID + XE_API_KEY in env → Xe. Otherwise → Frankfurter. Same fallback in Lambda and locally.

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Stack coverage

Built to match the full-stack requirements stated in Xe.com's developer role descriptions. Every item below is backed by code in this repo (S3 caching is scaffolded but not yet wired — noted below).

Requirement	Where it lives
TypeScript	src/, lambda/ — full codebase
MCP / agentic tooling	src/index.ts — stdio transport, 12 registered tools
AWS Lambda	lambda/handler.ts — REST API over all 10 tools
AWS SQS	lambda/alert-scheduler.ts → publishes; lambda/alert-processor.ts → consumes
AWS DynamoDB	lambda/alert-scheduler.ts — scans AlertsTable; SAM GSI on userId
AWS S3	src/s3-cache.ts — rate-history cache module + bucket in template.yml (scaffold; not yet wired into the deployed handler)
SQLite (local)	src/sqlite-store.ts — rate history cache (RATE_DB_PATH); live in fetchHistoricalSeries — cache hits skip API, misses store to DB; same schema works on PostgreSQL
AWS SES	lambda/alert-processor.ts — sends email on alert trigger
AWS API Gateway	template.yml — wired to XeMcpFunction
CloudWatch Events	template.yml — hourly schedule trigger on AlertSchedulerFunction
SAM / IaC	template.yml — full stack as code, sam build && sam deploy
CI/CD (GitHub Actions)	.github/workflows/ci.yml — test → build → verify; deploy.yml — deploy to ap-southeast-2
Docker	Dockerfile — multi-stage Alpine build for ECS / local
FX domain knowledge	optimal_send_window, volatility_analysis, correlation_analysis — log-return methodology

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Tests

npm test
# Test Suites: 5 passed
# Tests:       49 passed

Tests cover: zero-volatility edge cases, constant-return series, annualised vol formula (× √252), percentile distribution, Pearson r properties (perfect correlation, inverse, zero-variance), NZD/AUD co-movement sanity, SMA computation (period ordering, edge cases, distance from SMA), SQLite schema (PK constraints, upsert behavior, range query ordering, index verification), pair_summary math (percentile ranking, verdict labels, SMA(20) boundary).

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Why

Xe's developer job posting requires "daily use of agentic coding tools (Claude Code or equivalent)." I built the tool I'd want if I were working on Xe's FX data pipeline — one that brings rate intelligence into the coding environment without tabbing out.

The quant tools (volatility_analysis, optimal_send_window, correlation_analysis) come from time in currency markets. They're not wrappers around a stock analytics library; the math is direct log-return methodology with test coverage.

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Stack

TypeScript · Node.js · @modelcontextprotocol/sdk · Xe XECD API · Frankfurter API

License

MIT