get_usage_billing_line_items

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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. The description adds meaningful behavior: status is 'unbilled' (live snapshot) or 'billed' (already charged), which clarifies the data's temporal nature. It does not contradict annotations, and the extra detail is valuable beyond annotations.

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?

Two sentences with zero fluff. The first sentence establishes the tool's purpose and scope, the second explains the parameter. Information is front-loaded and every word earns its place. Highly concise.

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 one-parameter read-only tool, the description is complete. It explains what the tool does, what the parameter means, and the context relative to a sibling. There is no output schema, but the description implies the return is row-by-row detail. No critical information is missing for an agent to call it correctly.

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 only parameter 'status' has no schema description (0% coverage), so the description fully compensates by explaining its possible values and their meanings. It even notes the default is 'unbilled' and explains the live snapshot aspect. This is complete parameter documentation.

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 provides row-by-row usage detail backing the summary tool, and specifies the charge types (VPS/volume/IP/bandwidth). It distinguishes itself from get_usage_billing by explicitly mentioning it is the underlying detail. The purpose is unambiguous and specific.

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 when to use this tool: when you need row-level detail behind get_usage_billing's summary. It does not explicitly name alternatives or state when not to use it, but the connection to the summary tool gives clear context. It would benefit from an explicit 'use when you need line items' but is still clear enough.

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