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

The description adds format details beyond the annotations: it returns a mapping of code to name. Annotations already declare readOnlyHint and openWorldHint, which align. No contradictions.

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?

Single sentence, front-loaded with purpose, no fluff. Every word 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?

Given zero parameters, full annotation coverage, and a simple return format described, the description is fully complete for this tool.

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?

There are no parameters, and the schema coverage is 100% (empty). The description provides meaning about the output format, which is the only semantic needed. Baseline 4 is appropriate.

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?

Description clearly states the tool lists all supported ISO 4217 currency codes with their full names, using a specific verb and resource. It distinguishes from siblings 'convert' and 'get_rates' by specifying enumeration rather than conversion or rate retrieval.

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 implies the tool is used for retrieving the full set of supported currencies. While it does not explicitly state when not to use it or mention alternatives, the sibling context makes the usage clear. No exclusions are needed given the simple scope.

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