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

With no annotations, the description carries the full transparency burden. It usefully explains that results are measured in ieUnit and that a negative figure means loss of value relative to the ieUnit, but it does not disclose the exact return format (single value vs. series), pagination, or edge cases.

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 three concise sentences that front-load the action, provide concrete examples, and add interpretive guidance. Every sentence contributes meaningful information without redundancy.

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?

The description covers purpose, unit, period, available components, and result interpretation, while the schema fully documents the optional dates. However, because there is no output schema, the description stops short of specifying the exact response structure, which is the main gap.

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 already covers all three parameters with descriptions, including date defaults and the component enum. The tool description repeats the component list but does not add parameter-specific meaning, so the baseline of 3 applies.

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 uses a specific verb and resource: 'Compare one basket component against the ieUnit over a period of time', and clarifies the unit of measurement. It also distinguishes itself from siblings by emphasizing period-based comparison and neutral reference, which sets it apart from convert, value, and history tools.

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 gives clear use cases ('Answers questions such as how the Swiss franc, gold or Bitcoin held their value against a neutral reference'), which implies when to use the tool. However, it does not explicitly state alternatives or when not to use it, so it falls short of a 5.

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