Account identity and currency

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

Annotations already declare this as read-only, idempotent, and non-destructive, so the safety profile is covered. The description adds valuable behavioral context by instructing to 'call this once' and explaining that other tools return bare numbers in this currency, which helps the agent understand the tool's role in labeling amounts correctly without needing to repeat calls.

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 exactly two sentences: the first states the core function, the second gives usage guidance. Every word earns its place, with no redundant or filler content.

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 no-parameter tool, the description adequately covers what is returned (account identifier and currency) and why it matters (for labeling amounts). Annotations cover safety, and the absence of an output schema is acceptable because the description states the return values in plain terms. No further details are needed for an agent to select and invoke this tool correctly.

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 tool has zero parameters, so the schema is trivially fully covered. With no parameters, there is nothing to explain, and the baseline score of 4 applies as no additional parameter documentation is needed.

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 returns the account identifier and currency for all monetary figures, using a specific verb ('Returns') and resource. It explicitly distinguishes itself from sibling tools by explaining that other tools return bare numbers in this 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?

The description provides clear context on when to call this tool ('Call this once when you need to label amounts correctly') and explains the relationship with other tools. However, it does not explicitly name alternatives or state when not to use it, though the guidance implies it is only needed for labeling amounts.

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