Convert one amount into several currencies

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

With no annotations provided, the description carries full burden and does well: it discloses the consistent rate date, the per-currency rounding behavior, and that unknown targets are listed rather than causing failure. This is meaningful behavioral context beyond what the schema alone provides, though it does not cover every possible side-effect concern.

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?

Three sentences, each carrying a distinct necessary fact: core behavior with constraints, a usage pattern, and error handling. The description is front-loaded with the main action and has no filler 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 3-parameter tool with no annotations and no output schema, the description covers the core behavior, consistency guarantee, rounding rules, error handling, and a realistic use case. It does not describe the output structure or rate source details beyond 'ECB', but these are secondary to correct invocation.

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 coverage is only 33% (only 'to' has a description), so the description must compensate. It clarifies that 'amount' is a single amount converted into multiple currencies and that 'to' holds the target currencies, but it does not explicitly explain 'from' beyond being the source currency or specify formats beyond the schema pattern. Partial compensation.

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 states a specific verb ('Convert') and a specific resource ('one amount into several currencies'), and adds distinguishing constraints (same ECB rate date, rounding to each currency's minor units). This makes it clearly distinct from the sibling 'convert' tool, which converts one amount to one currency.

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 a concrete usage rule: for several lines at once (mixed-currency invoice lines), call it once per line so all lines share one rate date. It does not explicitly name the alternative 'convert' tool, but the guidance strongly implies when this multi-currency variant is appropriate.

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