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

No annotations are provided, so the description carries the disclosure burden. It does mention 'cached' exchange rates, which hints at potential staleness, but it does not disclose limitations like invalid currency handling, rounding behavior, or whether rates are updated. This is partial but not comprehensive behavioral transparency.

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, efficient sentence that starts with the primary verb 'Convert' and provides the essential resource and data source without any wasted words. It is perfectly sized for its purpose.

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?

Given the tool's simplicity (3 fully described parameters), the description adequately conveys the core function and data source. There is no output schema, so a note on return format would be nice, but the tool is straightforward enough that this absence does not hinder usability. The mention of caching adds important context for accuracy expectations.

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?

The input schema already provides full descriptions for all three parameters (amount, from, to) with ISO 4217 codes and exclusivity constraints. The description adds the 'cached ECB' context but does not introduce any additional parameter-level meaning beyond the schema, so the baseline of 3 is appropriate.

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 verb 'convert' and the resource 'amount between currencies', and adds the specific data source 'cached ECB exchange rates'. This distinguishes it from sibling tools like convert_timezone and makes the tool's purpose unmistakable.

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 gives clear context by specifying it converts an amount between currencies, and the mention of 'cached ECB exchange rates' implies when it applies (currency conversion). No explicit exclusions are needed since there is no direct competing currency tool among siblings, and this context is sufficient for selection.

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