billing_get_monthly_usage_summary

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

No annotations are provided, so the description must carry the burden of behavioral disclosure. It only says 'Get' which implies a read operation, but does not explicitly state it is read-only, nor does it mention any side effects, permissions, or limitations. The return format is partially described ('with service breakdown'), but the description lacks detail about what the summary includes (e.g., taxes, discounts) or any rate limits.

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 with no fluff. The main purpose is front-loaded in the first sentence, followed by clear parameter and return sections. It wastes no words and is easy to scan. It could be more descriptive, but it is appropriately sized for a simple getter tool.

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?

The tool is simple, and the output schema exists, so return values are covered by the schema. However, the description lacks usage context, such as when to use this tool versus other billing summaries (e.g., current month, last month, or listing history). It also does not mention any limitations or assumptions (e.g., only for past months). While not incomplete for basic use, it leaves room for an agent to mis-select among the many billing siblings.

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 provides only types and requirement, with zero description coverage. The description adds meaning by giving an example for year ('e.g., 2024') and a range for month (1-12). This clarifies acceptable values and expected format, which is essential for correct invocation. It does not fully explain the meaning of 'usage summary', but the parameters themselves are well documented.

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 it retrieves a monthly usage and cost summary, with a specific verb and resource. The parameters (year, month) indicate a specific time period, which distinguishes it from sibling tools like billing_get_current_month_summary or billing_get_last_month_summary, though it doesn't explicitly name them. The purpose is 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?

The description provides no guidance on when to use this tool versus other billing tools like billing_get_current_month_summary or billing_list_billing_history. There are no explicit usage conditions, alternatives, or exclusions. The parameters imply it's for a specific month, but this is not stated explicitly.

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