list_currencies

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

With no annotations, the description carries the full burden. It states a read-only action implicitly, but does not explicitly say it has no side effects, or mention any quirks like pagination or data freshness. For a simple list, this is adequate but not rich; a 3 reflects the lack of explicit behavioral guarantees.

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?

A single, front-loaded sentence with zero filler. Every word earns its place—'List', 'all supported currencies', and the parenthetical output detail. This is model-concise.

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?

Given the tool's simplicity—no parameters, no output schema, no complex behaviors—the description is complete. An agent knows exactly what to expect and can call it without further clarification. Nothing critical 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 baseline is 4. The description adds no parameter details, but none are needed since the input schema is empty. The description's mention of 'codes and names' clarifies the output, which indirectly defines the return semantics.

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 clearly states the verb 'List' and the resource 'all supported currencies' with output specifics (codes and names). It is unambiguous and distinct from siblings like convert_currency or get_latest_rates, which focus on operations rather than enumeration.

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 purpose implies when to use it—when an agent needs the set of available currency codes/names before performing conversions or rate lookups. It does not explicitly mention alternatives or exclusions, but the simplicity and distinctness of the action make the usage context clear enough.

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