Get the prepaid account balance

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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description reinforces this with 'changes nothing' and adds useful context about order refusal due to insufficient balance, which is not captured by the annotations. This extra context slightly exceeds the baseline given the already-complete annotations.

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 two sentences of appropriate length. The first sentence front-loads the core purpose, and the second adds essential usage guidance and an alternative reference. There is no unnecessary verbiage; every part earns its place.

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, parameterless read-only operation, the description fully covers what the agent needs to know: what is returned (balance and currency), why it matters (before debiting operations), and how to handle billed amounts. No additional details are required for 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?

The schema has zero parameters, and the description explicitly confirms it 'takes no arguments'. While this is redundant with the schema, it provides clear confirmation to the agent, eliminating any ambiguity. Given the perfect schema coverage and the explicit statement, a score above baseline is warranted.

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 action ('Returns') and the resource ('the account’s prepaid balance and its currency'). It also distinguishes this tool from sibling eurodns_invoice_get by explicitly noting that billed amounts are handled elsewhere, making its purpose unambiguous.

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 gives specific guidance on when to use the tool: 'Read it before any tool described as debiting credit' and explains the consequence of an insufficient balance ('an order is refused'). It also explicitly names an alternative (eurodns_invoice_get) for already-billed amounts, covering both when-to-use and when-not-to-use.

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