Get usage statements

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful context — per-period family grouping and pagination — but does not describe auth requirements, rate limits, or return shape beyond the grouping hint.

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?

Front-loaded with the core purpose, then the parenthetical examples and the invoice distinction, ending with pagination. Every sentence earns its place; only the trailing 'Paginated.' is slightly clipped but still informative.

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 read-only, single-parameter listing tool with no output schema, the description gives enough: what it returns (itemized statements grouped by family per period), how it differs from invoices, and pagination. Missing only minor details like sort order or default page behavior.

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?

Only one parameter (page) with 100% schema coverage, so the schema already documents it. The description's 'Paginated' note signals the pagination model but adds no detail beyond what the schema's page description provides. Baseline 3 applies.

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?

States a specific verb (Get) and resource (itemized usage-billing statements for the account), and clarifies the granularity (per-period totals by family) with concrete examples like Firecracker Functions usage and VDS snapshots. It also explicitly separates itself from the invoice siblings by noting these are metered/usage-based charges.

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 routes the agent well: 'This is where metered/usage-based charges show up, separate from invoices' tells the caller when to pick this over list_invoices/get_invoice. It doesn't cover exclusions or failure/auth conditions, but the primary alternative is named implicitly.

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