# list_currencies

List all supported currencies with name, decimal precision, minor units, and whether the pair is derived (triangulated). Use this before other tools to discover valid currency codes.

Agent View of the PolicyLayer registry record for `list_currencies`. HTML page: https://policylayer.com/tools/dev-exchangerate-mcp/list-currencies

## Facts

- Tool: `list_currencies`
- Server: Exchangerate Dev (`https://api.exchangerate.dev/v1/mcp/`) — https://policylayer.com/tools/dev-exchangerate-mcp.md
- Homepage: https://github.com/https://api.exchangerate.dev/v1/mcp/
- Risk category: Read (Low risk)
- Registry record: grade C, identity unverified
- Server auth posture: open
- Server rate-limited: yes
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "list_currencies",
    "arguments": {}
  }
}
```

## Why list_currencies is rated Low

This tool retrieves static metadata about supported currencies (names, decimal precision, minor units, derivation status). It performs no modifications, deletions, code execution, or financial transactions. It is a pure read operation with minimal blast radius—misuse would only result in unnecessary API calls or information disclosure of public currency data.

From the tool's own definition: "Tool name 'list_currencies' and description 'List all supported currencies' indicates a retrieval operation with no side effects."

## Use case

AI agents call list_currencies to retrieve information from Exchangerate Dev without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Exchangerate Dev:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_currencies": {}
  }
}
```

## Other tools on Exchangerate Dev (4)

- `convert` — Read — https://policylayer.com/tools/dev-exchangerate-mcp/convert.md
- `get_range` — Read — https://policylayer.com/tools/dev-exchangerate-mcp/get-range.md
- `get_rate` — Read — https://policylayer.com/tools/dev-exchangerate-mcp/get-rate.md
- `search_docs` — Read — https://policylayer.com/tools/dev-exchangerate-mcp/search-docs.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=dev-exchangerate-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/dev-exchangerate-mcp