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

Annotations already declare read-only, idempotent, non-destructive behavior. The description adds useful context beyond annotations: the 30-day window, key-vs-account scope, and the transcription/server burn split. It does not describe rate limits or full return shape, but the added behavioral detail is substantial.

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 three concise sentences with no wasted text. The scope and key data are front-loaded, followed by the split and parameter units.

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 usage tool with no output schema, the description covers the essential window, scope, split, and parameter units. It is slightly incomplete because it does not clarify the default date-range behavior when from/to are omitted or what the response structure looks like.

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 carry parameter meaning. It correctly documents that from and to are unix milliseconds, which is valuable. However, it does not explain default behavior when these optional parameters are omitted, nor whether from/to override or refine the 30-day window.

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 resource and scope: 30-day credit usage for the current key or for the whole account when the key has been claimed. It also specifies that the data splits transcription and server burn. It does not explicitly distinguish itself from sibling tools such as get_balance, so it is clear but not sibling-differentiated.

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 explains the data scope but gives no explicit guidance on when to use this tool versus get_balance or other sibling tools. The only conditional statement is about account-level scope when the key has been claimed, not about when to invoke the tool.

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