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

With no annotations provided, the description carries the full burden of disclosing behavior. It only mentions 'official' and 'free', but does not explain response format, error behavior, data freshness, or any constraints. This is insufficient for an agent to understand the tool's operational characteristics.

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 extremely concise with no fluff, and the key information is front-loaded. However, it is so terse that it borders on under-specification, hence not a perfect score.

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 simplicity, the description still lacks critical context: no usage scenarios, no return description, no parameter details, and no differentiation from sibling tools. An agent would struggle to know when to invoke this tool and how to construct a valid request.

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 description coverage is 0%, so the description must compensate. It labels the parameters as 'base' and 'symbols', which clarifies their roles, but provides no details about acceptable values, format, or examples. This adds minimal meaning beyond the bare schema field names.

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 identifies the resource as official ECB cross-rates and mentions the base+symbols scope, distinguishing it from sibling tools like kzt_rates. However, it lacks an explicit verb like 'get' or 'retrieve', making it slightly less direct than ideal.

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?

There is no guidance on when to use this tool versus alternatives such as kzt_rates or how it fits into a workflow. Sibling tools are not referenced, and no exclusions or prerequisites are mentioned.

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