exchange-rate.getLatestRates

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows it's a safe read. The description adds no behavioral detail beyond the annotations—e.g., it doesn't mention that rates are based on a default base currency or that it returns a snapshot. However, with annotations covering safety, a 3 is appropriate because no contradiction and minimal added value.

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 that is concise and front-loaded, with no unnecessary words. It could be slightly more informative, such as mentioning what the default base currency is, but it is appropriately brief.

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 tool has zero parameters and a simple output schema (likely a currency map), and annotations cover safety. The description is adequate but lacks details such as the default base currency or whether the rates are relative to a specific base (e.g., USD). Since it's a simple read tool, a concise description is sufficient, but missing the default base could mislead the agent.

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 zero parameters in the schema, and the description mentions 'base currency,' implying that the tool might have a default base currency or that the base currency is fixed. Since there are no parameters to document, the description does not need to add parameter semantics. The mention of 'base currency' provides some context, and given no parameters, a high score is justified.

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 retrieves latest exchange rates for a base currency, with a specific verb and resource. It does not differentiate from other exchange-rate tools (e.g., might be a sibling with historical rates), but no such sibling exists in the provided list; among the listed siblings, it is unique.

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 no guidance on when to use this tool versus alternatives, and does not mention any context such as the need for a base currency specification or typical use cases. Since there are no sibling tools for exchange rates, the lack of alternatives is less critical, but no usage context is given.

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