Frankfurter

List currencies

list_currencies

Read-only

Find currency, metal and crypto codes by code or name. Returns {code:name}; omit query for all, including historical currencies.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

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

Input Schema

Name	Required	Description	Default
`query`	No	Code or name fragment, case-insensitive. Exact codes take priority.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedNov 8, 2026

addedInput schema / additionalProperties
```
Added value: +false
```

addedInput schema / properties / query

Added value: +{
+  "description": "Code or name fragment, case-insensitive. Exact codes take priority.",
+  "minLength": 1,
+  "type": "string"
+}

AddedJul 27, 2026

TDQS

A3.9/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations declare readOnlyHint and openWorldHint, so the safety profile is covered; the description adds genuinely new behavior — the {code:name} return shape and the fact that a query-less call includes historical currencies, which an agent could not infer from the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, front-loaded with purpose, then return shape, then the omit case. No filler or restatement of the title.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description usefully sketches the return shape ({code:name}) and the all-results behavior, which is enough to call the tool correctly. Ordering and whether historical entries are flagged are unstated but minor for a one-parameter lookup.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and documents the single query param's matching semantics, so baseline 3 applies; the description earns an extra point by explaining the omit-query behavior and the historical-inclusion side effect, which the schema does not state.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource set: 'Find currency, metal and crypto codes by code or name.' An agent can tell this is a code lookup/list tool rather than a conversion or rate-fetch tool, though it never names the sibling tools it differs from.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear guidance for the degenerate case ('omit query for all, including historical currencies') but no guidance on when to prefer this over convert or get_rates, nor any exclusion criteria.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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