list_currencies

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively adds context beyond the input schema by specifying that no API key is needed (implying no authentication requirements) and that data is cached for 24 hours upstream (indicating potential rate limits or freshness considerations). However, it does not detail response format or error handling.

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 highly concise and front-loaded, consisting of two sentences that efficiently convey the tool's purpose, key features (no API key, caching), and scope. Every sentence adds value without redundancy, making it easy to parse quickly.

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 low complexity (0 parameters, no output schema, no annotations), the description is largely complete, covering purpose, authentication, and caching. However, without an output schema, it could benefit from briefly mentioning the return format (e.g., list of objects with code, name, symbol) to fully guide usage.

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 input schema has 0 parameters with 100% coverage, so no parameter documentation is needed. The description appropriately does not discuss parameters, maintaining focus on the tool's purpose and behavior, which aligns with the baseline expectation for tools with no parameters.

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 specific action ('List all supported currencies') and resource ('currencies'), with explicit details on what information is included ('code, name, and symbol'). It effectively distinguishes from sibling tools like get_exchange_rate or get_historical_rates, which focus on rates rather than listing 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 by stating 'No API key required' and 'Cached 24h upstream', which helps determine when to use this tool (e.g., for basic currency info without authentication). However, it does not explicitly mention when not to use it or name alternatives among siblings, such as get_rates_authenticated for authenticated rate data.

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