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 only states the data source and frequency, but leaves unresolved whether this returns a time series, a single latest snapshot, the exact date range, or any rate limits/pagination. This is minimal and lacks detail about output structure or side effects.

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 a single sentence of ten words, immediately stating the currencies and frequency. There is no filler, and it is appropriately sized for a tool with no parameters or complex behavior.

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 lack of an output schema and annotations, the description should clarify what is returned, but it only mentions the currencies and daily frequency. It does not specify whether data is a full history or latest only, nor the structure of the response. It is adequate for a simple tool but leaves room for ambiguity.

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 zero parameters, so the description does not need to add parameter semantics. Per the rubric, zero parameters default to a baseline of 4. The description adds nothing extra, but none is needed.

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 'EUR exchange rates vs USD, GBP, JPY, CHF, CNY' clearly identifies the resource (exchange rates) and distinguishes it from sibling tools like ecb_rates or ecb_inflation. However, it lacks an explicit verb such as 'get' or 'retrieve', making it a noun phrase rather than a full action statement.

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 mention of 'Daily from ECB' implies usage for accessing daily ECB EUR exchange rates for the listed currencies. Yet it does not explicitly state when to use this tool over alternatives among the many related ECB tools, nor does it provide any exclusions or alternative tool names.

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