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.

SERVERExchangerate Dev SOURCEhttps://api.exchangerate.dev/v1/mcp/

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade C, identity unverified Pull the record →

This record as markdown: /tools/dev-exchangerate-mcp/list-currencies.md

WHAT IT DOES

What list_currencies does on Exchangerate Dev

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.

RISK

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 definition Tool name 'list_currencies' and description 'List all supported currencies' indicates a retrieval operation with no side effects.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs list_currencies safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Exchangerate Dev, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For list_currencies, this is the rule to start with:

list_currencies Allowed

list_currencies is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

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

ALLOW ONLY THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Exchangerate Dev, apply this rule, and every list_currencies call is checked against it from then on.

FAQ

Questions about list_currencies

What does the list_currencies tool do? +

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. It is categorised as a Read tool in the Exchangerate Dev MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_currencies? +

Register the Exchangerate Dev MCP server in PolicyLayer and add a rule for list_currencies: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Exchangerate Dev. Nothing to install.

What risk level is list_currencies? +

list_currencies is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit list_currencies? +

Yes. Add a rate_limit block to the list_currencies rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block list_currencies completely? +

Set action: deny in the PolicyLayer policy for list_currencies. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides list_currencies? +

list_currencies is provided by the Exchangerate Dev MCP server (https://api.exchangerate.dev/v1/mcp/). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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