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

Annotations already declare read-only, idempotent, non-destructive behavior. The description adds valuable context beyond annotations: the method and citations are stated explicitly, currency coverage (~30 majors vs ~90 others), and the date-range behavior (since 1999). No contradiction with annotations.

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, front-loaded with the main purpose, and every clause adds useful information. It avoids redundancy and is easy to scan.

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?

For a tool with no output schema, the description reasonably explains the conversion sources, date formats, and currency coverage, plus notes that method and citations are included in the response. It could be slightly richer by stating the output shape, but it is adequate for the tool's complexity.

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 descriptions cover 75% of parameters (to, from, date), giving ISO codes and date format. The description goes further by explaining the meaning of the date format ('YYYY-MM-DD' for daily, 'YYYY' for annual average) and giving concrete currency examples (BBD, XCD, JMD, KES), which helps select correct parameter values.

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 converts an amount between currencies using official reference rates, with specific sources (ECB daily, World Bank annual). This distinguishes it from sibling tools like inflation_adjust or get_series, and the verb 'Convert' plus resource 'currencies' is specific.

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?

It provides clear contextual guidance on when to use daily ECB rates versus World Bank annual rates, and exactly how to pass the date parameter. However, it does not explicitly mention alternatives or when not to use this tool relative to sibling tools.

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