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

Annotations already declare readOnlyHint=true, so the read-only nature is covered. The description adds the timeframe scoping and the Orb API endpoint, but it does not disclose return shape, pagination, or how grouping/granularity affect the result.

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 operation and timeframe, with a compact API reference. There is no filler or repetition.

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 and no usage-context guidance, the description leaves an agent uncertain about the response format and how group_by/granularity shape the returned data. The schema covers the parameters but not the full behavior needed for a multi-option usage query.

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 schema already documents all five parameters. The description adds little beyond implying timeframe_start/timeframe_end, which is not enough to raise the baseline score.

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 clear verb and resource: it gets metered usage for a subscription over a timeframe. It is distinguishable from 'subscription' or 'subscription_costs' siblings by the word 'usage', but it never explicitly names the sibling tools or the differentiators, so it falls just short of full differentiation.

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 gives no guidance on when to prefer this tool over close siblings like orb_get_subscription_costs or orb_get_subscription. There is no when-to-use, when-not-to-use, or alternative reference.

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