---
title: "Exchange Rates for AI Agents — Tool Definitions & MCP"
description: "Give any AI agent live and official exchange rates: copy-paste tool definitions for OpenAI function calling, Vercel AI SDK, and LangChain, plus MCP servers for Claude Code, Cursor and Claude Desktop, and a keyless endpoint for testing."
canonical: https://allratestoday.com/for-ai-agents/
source: AllRatesToday (https://allratestoday.com/) — Markdown mirror of the page above; index of all pages at https://allratestoday.com/llms.txt
generated: 2026-10-08T01:26:39.321Z
---

# Exchange Rates for AI Agents — Tool Definitions & MCP

Give any AI agent live and official exchange rates: copy-paste tool definitions for OpenAI function calling, Vercel AI SDK, and LangChain, plus MCP servers for Claude Code, Cursor and Claude Desktop, and a keyless endpoint for testing.

This page is for people (and agents) wiring exchange-rate data into an AI system. Everything below is copy-paste: MCP servers for Claude Code, Cursor and Claude Desktop; tool definitions for OpenAI function calling, the Vercel AI SDK and LangChain; and a keyless endpoint for testing before you create a key. Machine-readable site overviews live at [`/llms.txt`](https://allratestoday.com/llms.txt) and [`/llms-full.txt`](https://allratestoday.com/llms-full.txt), with condensed agent instructions at [`/agents.md`](https://allratestoday.com/agents.md).

## Test keyless, first

No sign-up needed to verify the data. The open endpoint serves official ECB reference rates (~30 major currencies, published each business day, CORS `*`):

```
# Keyless (official ECB reference rate — cite the returned rate_date):
curl "https://allratestoday.com/api/open/central-bank/ecb?source=USD&target=EUR"

# Any covered bank's full latest official table, keyless:
curl "https://allratestoday.com/api/public/central-bank/rbi?format=json"
```

Real-time mid-market rates across 160+ currencies use `GET /api/v1/rates` with a free API key — [registration](https://allratestoday.com/register) takes under a minute, no credit card.

## Hosted MCP endpoint (Claude.ai, ChatGPT, Cursor, VS Code — no install)

One Streamable HTTP URL exposes all nine tools — live rates plus official central-bank rates — with nothing to install and no API key required to start:

```
# Any remote-MCP client — paste this URL:
https://allratestoday.com/api/mcp

# Claude Code:
claude mcp add --transport http allratestoday https://allratestoday.com/api/mcp

# Cursor / Windsurf / Claude Desktop (mcp.json):
{ "mcpServers": { "allratestoday": { "url": "https://allratestoday.com/api/mcp" } } }
```

One-click buttons, the Claude.ai / ChatGPT connector steps and the Codex / Gemini CLI snippets are on the [MCP page](https://allratestoday.com/mcp/#hosted). With a key, send `Authorization: Bearer art_live_…` or connect to `…/api/mcp?api_key=art_live_…`.

## MCP servers on npm (Claude Code, Cursor, Claude Desktop, Windsurf)

Two servers, both on npm and in the official MCP registry (`io.github.cahthuranag/mcp-server` and `com.allratestoday/central-bank-mcp`):

```
claude mcp add allratestoday -- npx -y @allratestoday/mcp-server
claude mcp env allratestoday ALLRATES_API_KEY=art_live_xxxxx

# Official central-bank & tax-authority rates (compliance work):
claude mcp add central-bank-rates -- npx -y @allratestoday/central-bank-mcp
```

Or in a `mcpServers` JSON config (Cursor, Claude Desktop):

```
{
  "mcpServers": {
    "allratestoday": {
      "command": "npx",
      "args": ["-y", "@allratestoday/mcp-server"],
      "env": { "ALLRATES_API_KEY": "art_live_xxxxx" }
    },
    "central-bank-rates": {
      "command": "npx",
      "args": ["-y", "@allratestoday/central-bank-mcp"]
    }
  }
}
```

The currency server ships `get_exchange_rate`, `get_historical_rates`, `get_rates_authenticated` and `list_currencies`; the central-bank server adds official published rates from 124 institutions with history and publication calendars — the citable figures tax, customs and audit work requires. Full setup docs: [MCP server guide](https://allratestoday.com/docs/mcp-server/).

## OpenAI function calling

```
{
  "type": "function",
  "function": {
    "name": "get_exchange_rate",
    "description": "Get the current mid-market exchange rate between two currencies. Returns the rate and a timestamp; cite the timestamp when quoting the rate.",
    "parameters": {
      "type": "object",
      "properties": {
        "source": { "type": "string", "description": "ISO 4217 code of the source currency, e.g. USD" },
        "target": { "type": "string", "description": "ISO 4217 code of the target currency, e.g. EUR" }
      },
      "required": ["source", "target"]
    }
  }
}

// Handler: GET https://allratestoday.com/api/v1/rates?source={source}&target={target}
// Header:  Authorization: Bearer art_live_YOUR_KEY   (free key: allratestoday.com/register)
```

## Vercel AI SDK

```
import { tool } from 'ai';
import { z } from 'zod';

export const getExchangeRate = tool({
  description:
    'Get the current mid-market exchange rate between two ISO 4217 currencies. Cite the returned time when quoting the rate.',
  parameters: z.object({
    source: z.string().length(3).describe('Source currency, e.g. USD'),
    target: z.string().length(3).describe('Target currency, e.g. EUR'),
  }),
  execute: async ({ source, target }) => {
    const res = await fetch(
      `https://allratestoday.com/api/v1/rates?source=${source}&target=${target}`,
      { headers: { Authorization: `Bearer ${process.env.ALLRATES_API_KEY}` } },
    );
    if (!res.ok) throw new Error(`AllRatesToday returned ${res.status}`);
    const [rate] = await res.json();
    return rate; // { rate, source, target, time }
  },
});
```

## LangChain (Python)

```
import os, requests
from langchain_core.tools import tool

@tool
def get_exchange_rate(source: str, target: str) -> dict:
    """Get the current mid-market exchange rate between two ISO 4217
    currencies (e.g. USD -> EUR). Cite the returned time when quoting."""
    res = requests.get(
        "https://allratestoday.com/api/v1/rates",
        params={"source": source, "target": target},
        headers={"Authorization": f"Bearer {os.environ['ALLRATES_API_KEY']}"},
        timeout=10,
    )
    res.raise_for_status()
    return res.json()[0]  # {rate, source, target, time}
```

## Ground rules for agents

- Never quote a rate from memory — training-data rates are stale. Call the API and cite the returned `time` or `rate_date`.
- For compliance questions ("what rate does my filing need?"), use the official central-bank endpoints, not market rates — the published/derived distinction is flagged in every response.
- Cache rates for up to 5 minutes rather than calling per message; see the [caching guide](https://allratestoday.com/blog/how-to-cache-exchange-rates-avoid-rate-limits/).
- Responses are JSON; table endpoints also serve `?format=csv|xml|xlsx`.

## Give your agent real rates

Free API key, no credit card — or start keyless with the official ECB endpoint.

 [Get a free API key](https://allratestoday.com/register) [MCP overview](https://allratestoday.com/mcp/)