billing_summary

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

The description discloses that the tool returns a cost breakdown and recent charges and that `days` controls the lookback window. With no annotations, it would benefit from explicitly stating that this is a read-only operation with no side effects on billing or instances. It adds useful output and scope detail but not complete behavioral disclosure.

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 concise sentences front-load the overall purpose and then clarify the relevant parameter. There is no filler, redundancy, or buried context. This is an appropriately sized and well-structured description.

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?

With no output schema, the description does explain the main return values: hourly cost breakdown plus most recent charges. Optional and default parameter behavior is covered by the schema, and the tool's complexity is low. It is complete enough for an agent to select and call the tool, though read-only status is only implied.

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 description coverage is 100%, so the baseline is 3, and the description mostly restates the `days` meaning already in the schema. The `limit` parameter is not mentioned in the description but is fully documented by the schema. This meets but does not exceed the baseline.

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 identifies a billing-summary resource with specific output elements: per-instance hourly cost breakdown, GPU/disk/storage, total $/hr, and recent charges. This distinguishes it from sibling tools that deal with GPU listings, offers, volumes, and instances. It lacks an explicit verb like 'get' or 'view', so it stops just short of a top score.

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 phrase 'Overall billing' provides clear context that this tool is for billing inquiries rather than resource management, and no sibling tool covers billing. However, it does not explicitly state when not to use it or name an alternative. This is clear context without exclusions, which matches a 4.

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