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

With no annotations provided, the description carries the full burden. It successfully discloses the return values ('conversion rate and result') and data source ('ExchangeRate-API'), plus scope ('160+ currencies'). However, it omits rate limits, authentication requirements, and precision/rounding behavior.

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 single sentence is efficiently structured with the action first ('Convert amount'), followed by scope ('160+ currencies'), and return value disclosure. Every clause earns its place; no redundancy or filler.

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 without output schema, the description adequately compensates by stating what gets returned. It covers the essential behavioral context given the tool's simplicity, though explicit mention of the default amount behavior (implied by schema) would strengthen it further.

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%, establishing a baseline of 3. The description adds value by noting '160+ currencies supported,' which provides context for valid 'from' and 'to' parameter values beyond the basic ISO code format in the schema.

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 uses a specific verb ('Convert') with clear resource ('currencies') and scope ('any two currencies'). It effectively distinguishes from sibling 'currency.exchange.latest' by emphasizing the conversion action with an amount, versus merely retrieving rates.

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?

While the description implies usage through the word 'Convert' (suggesting use when transforming monetary values), it lacks explicit when-to-use guidance or contrast with sibling 'currency.exchange.latest'. The agent must infer this is for calculated conversions versus rate lookups.

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