list_billing_invoices_by_period

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

No annotations are provided, so the description carries full burden. It does not state that it is a read-only operation, nor does it mention authorization requirements, pagination, or error handling. It only discloses the monthly constraint and FOCUS v1.3 output option.

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?

Three sentences, no filler. First sentence states purpose, second gives constraint, third provides multi-call guidance, fourth adds output format note.

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?

Despite simplicity, the description covers the one-month constraint and multi-call scenario, but lacks details on response format, error handling, or required permissions. The FOCUS note is a plus.

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?

Schema coverage is 100% and the description does not add additional meaning beyond what the schema already provides for the 'period' parameter.

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 lists invoices for a specific billing period in YYYY-MM format, with the constraint of one month per call. This distinguishes it from sibling tools like list_billing_invoices which likely lists all invoices without a period filter.

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?

Provides explicit guidance: one month per call, and instructs to calculate and ask permission for longer ranges. Does not explicitly mention alternative tools but the context is clear.

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