List the currencies supported for exchange-rate lookups, with their full names.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
| count | Yes | Number of supported currencies | |
| source | Yes | ||
| currencies | Yes | ISO 4217 codes mapped to currency names |
Changes observed during successful MCP inspections. Dates show when Glama detected each change.
Output schema / (root)Previous value: -nullNew value: +{
+ "additionalProperties": false,
+ "properties": {
+ "count": {
+ "description": "Number of supported currencies",
+ "type": "integer"
+ },
+ "currencies": {
+ "additionalProperties": {
+ "maxLength": 128,
+ "minLength": 1,
+ "type": "string"
+ },
+ "description": "ISO 4217 codes mapped to currency names",
+ "maxProperties": 256,
+ "minProperties": 1,
+ "propertyNames": {
+ "pattern": "^[A-Z]{3}$"
+ },
+ "type": "object"
+ },
+ "source": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "count",
+ "currencies",
+ "source"
+ ],
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. The simple read-only nature is clear from 'List', and the description adds that it returns full names, which is useful behavioral detail. For a simple listing operation, this is adequate transparency; it doesn't hide side effects or require prerequisite knowledge.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, front-loaded sentence that states the purpose and a key output detail with no wasted words. Every element earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool is a simple zero-parameter list operation. The description explains what is returned (currencies and their full names), the output schema provides structure, and there are no prerequisites or edge cases to mention. Nothing an agent needs to invoke it correctly is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool has zero parameters, so the description cannot add parameter meaning. The baseline of 4 applies because there are no parameters to document, and nothing is missing.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb ('List'), names a clear resource ('currencies supported for exchange-rate lookups'), and specifies the output includes full names. This clearly distinguishes it from sibling tools like fx_convert, fx_historical, fx_rates, and fx_timeseries, which all perform operations on rates rather than listing supported currencies.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides clear context: this tool is for discovering which currencies are available for exchange-rate lookups. It doesn't explicitly name alternatives or exclusions, but the context is sufficient for an agent to understand when to call it versus the rate-operation siblings.
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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