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

No annotations were provided, so the description carries the behavioral burden. It discloses that values are recalculated once per day, returns multiple data points (USD, CHF, EUR, 24h change, last update date), and explains the underlying basket, giving the agent a clear understanding of the tool's behavior and output.

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 two sentences long, front-loads the main purpose, and provides essential context without unnecessary fluff. The explanation of what an ieUnit is adds value but is not overly verbose.

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?

Without an output schema, the description adequately explains what the tool returns (value in USD, CHF, EUR, 24-hour change, last update date) and the freshness policy. It is complete enough for a simple single-parameter 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?

Schema coverage is 100%, and the schema's parameter description already explains the 'currency' enum and that all three currencies are always included. The description adds no additional parameter semantics beyond what the schema provides, so baseline 3 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?

The description clearly states the tool's function with a specific verb and resource: 'Get the current value of one ieUnit.' It also distinguishes the tool from siblings by focusing on the 'current' value and mentioning daily recalculation, differentiating it from ieunit_history or ieunit_compare.

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 a direct usage example: 'Use this for questions like "what is one ieUnit worth right now"' which clearly indicates when to use the tool. It does not explicitly state when not to use it, but for a simple current-value tool this is sufficient guidance.

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