getBillingInfo

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

No annotations are provided, so the description carries the burden of behavioral disclosure. It mentions that monetary values are in the smallest currency unit, which is useful for interpreting output. However, it does not disclose whether this is a read-only operation, any data limits, or response format details. This is adequate for a read-like tool but not fully transparent.

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 concise, two sentences, with the core function front-loaded. The currency unit note is valuable and placed at the end. There is minimal waste, though the second sentence could be seen as extra, but it earns its place for interpretability.

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 (single parameter, no output schema), the description is complete enough. It lists the included fields, which compensates for the lack of an output schema. The only omission is potential authentication requirements, but for a billing read tool, it's reasonably complete.

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 already documents the parameter fully (accountId as string with description 'Ad account ID (act_XXX) or account name'), and schema coverage is 100%. The description adds no additional parameter semantics beyond what the schema provides, so the baseline score 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 tool's purpose: retrieving billing and financial information for an ad account, listing specific data fields such as pending balance, total spend, spend cap, payment method details, and tax info. It distinguishes itself from sibling tools like getAccountInfo by focusing on billing-specific details.

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 billing information is needed, but it does not explicitly state when not to use this tool or mention alternatives. For example, it doesn't clarify that getAccountInfo might be more appropriate for general account details. The context is clear for billing purposes, but lacks explicit exclusions.

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