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

With no annotations, the description carries the full behavioral burden. The word 'covered' usefully signals that the list is scoped to the service's supported set rather than all ISO 4217 codes, but nothing states whether results are paginated, ordered, cached, or whether the list can change over time. For a zero-parameter read tool the risk is low, but the disclosure is thin.

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?

One sentence, front-loaded with the verb and resource, with the parenthetical standard and the returned fields compactly appended. Nothing is redundant and nothing is missing that would need to be said first.

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?

For a zero-param, annotation-free list tool with no output schema, the description covers the essentials: what is listed, the code standard, and the fields returned. Only the exhaustiveness/ordering of the result set is left undefined, a minor gap given the tool's simplicity.

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 takes zero parameters, so there is no parameter meaning to add; the baseline for a no-param schema applies. The description does spend its words on output fields instead, which is the right use of space.

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?

A specific verb plus resource ('List covered currencies') with the ISO 4217 standard named and the returned fields enumerated (issuing country and issuer). An agent can immediately tell this is an enumeration of supported currencies rather than a lookup or conversion tool, and it is clearly distinct from the calendar/exchange/centre siblings. It stops short of explicitly contrasting with any sibling, which keeps it at 4.

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?

There is no explicit when-to-use or when-not-to-use statement, but the purpose is narrow enough that usage is implied: call it to discover which currencies the dataset covers, e.g. before querying currency_non_clearing_days. No prerequisites or alternative routing are mentioned.

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