Usage Get

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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the half-open range semantics and 'preserve upstream units,' which is useful behavioral context beyond the schema. However, it does not disclose what the response contains or whether any aggregation/formatting occurs, so it adds only modest value.

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?

The description is a single sentence that front-loads the core action and resource, then adds the key scoping detail. Every word earns its place; there is no fluff or repetition of schema field names.

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 read-only tool with two parameters and an output schema, the description covers the essential semantics: what is fetched and the date-range behavior. The output schema presumably documents the return shape, so the lack of return details is acceptable. It could be more complete with an explicit 'use this for account-level usage' note, but it is adequate.

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 0%, so the description must compensate. It does clarify that the two parameters form a half-open date range, which is meaningful. However, it does not explain the format constraints beyond YYYY-MM-DD or the relationship between starting_on and ending_before in detail, so the compensation is partial.

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 states a specific verb ('Get') and resource ('account usage'), and adds a precise scope: a half-open YYYY-MM-DD date range. It does not explicitly distinguish itself from sibling tools, but the resource is clear enough that an agent can infer it is a read-only usage query.

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 usage by naming the date-range parameters, but it does not state when to use this tool versus alternatives or mention any exclusions. The half-open range hint is useful, but there is no explicit guidance about prerequisites or when a different tool would be more appropriate.

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