get_usage

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

The readOnlyHint annotation already signals the safe read-only nature. The description adds that the response includes 'full daily metrics,' which is useful return-oriented context, but it does not disclose other behavioral traits like error handling or authentication requirements. This is adequate given the annotation coverage.

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?

A single, front-loaded sentence with no filler. It efficiently communicates the action, resource, identifier, and a key output characteristic.

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 single-parameter read tool with a readOnly annotation, the description covers the essential elements: what, which resource, how to identify it, and a hint of the return content ('full daily metrics'). Without an output schema, a bit more specificity about the metrics would improve completeness, but the current level is sufficient for basic invocation.

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%, and the parameter 'utilizationId' is self-explanatory. The description only reaffirms the parameter name without adding new semantic detail, so it stays at the baseline for fully-covered schemas.

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 uses a specific verb ('Get'), identifies the resource ('Sub-Account usage record'), and states the lookup key ('utilization ID'). It also distinguishes itself from siblings like list_usages (specific vs. list) and get_control_account_usage (sub-account vs. control account).

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 clearly implies the right context: use when you have a utilization ID and need a single sub-account usage record with daily metrics. It does not explicitly name alternatives or exclusions, but the 'Sub-Account' and 'specific' wording provide enough directional guidance relative to the sibling tools.

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