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

No annotations are provided, so the description carries the full burden. It explicitly states 'Read-only' and 'price 0.0 (free)', plus 'fetched on demand', which are key behavioral traits. It does not disclose failure modes or rate limits, but for a simple conversion tool this is reasonably transparent.

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?

Two sentences, front-loaded with the main verb and resource. Every sentence adds value: the first explains what and how, the second covers return values and safety/cost. No wasted words.

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 simple 3-parameter conversion tool, the description covers purpose, data source, return value (rate and converted amount), and important context (read-only, free). No output schema exists, but the description explicitly mentions what is returned. It is complete 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 description coverage is 100%, with clear descriptions for amount, from, and to (ISO 4217). The description does not add any additional parameter-level semantics beyond the schema; it only mentions 'between currencies' at a high level. Baseline 3 is appropriate since the schema handles the details.

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 Frankfurter/ECB public FX rates and returns the rate and converted amount. This is a specific verb+resource pairing that distinguishes it from siblings like price_oracle_convert by emphasizing the free, keyless public rate source.

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 clear context (free, keyless, on-demand public rates, read-only, price 0.0) that implies when to use this tool, but it does not explicitly exclude alternatives or name sibling tools. It gives enough context for an agent to infer it is the low-cost/read-only option, but no explicit when-not guidance.

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