get_balance

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

The annotations already provide readOnlyHint=true, indicating a safe read operation. The description adds that the tool returns both balance and currency, giving some context about the output. However, it does not disclose any other behavioral traits such as authentication requirements, rate limits, or potential errors. Given the read-only nature, the description is minimally sufficient.

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, concise sentence: 'Return prepaid credit balance and currency.' Every word is meaningful, and it is front-loaded with the action. No unnecessary information is present.

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 tool with no output schema, the description completely covers what the tool returns (balance and currency). No further context is needed to understand the tool's purpose or use.

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 parameter semantics are trivial. The schema covers 100% of parameters (none). Per the rubric, 0 params earns a baseline of 4. The description does not need to explain parameters.

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's function: 'Return prepaid credit balance and currency.' It uses a specific verb ('Return') and resource ('prepaid credit balance and currency'), which unambiguously distinguishes it from sibling tools like topup_balance (which adds credit) or whoami (which returns account identity).

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 implies usage when the user needs to know their prepaid credit balance, but it does not explicitly state when to use this tool versus alternatives, nor does it mention any exclusions. For instance, it does not say 'use this before placing an order' or 'for top-ups, use topup_balance instead.'

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